A few preliminary remarks and imaginations:

1. I guess the basic meaning of 'mucus' could be the slimy mixture of land and sea squeezing up between your toes when treading on the muddy beach at low tide.

This idea points to the cosmic border line between 'land' and 'sea', i.e. the nourishing place after the vai season has passed away - spring. The 'birth of new land' comes with 'high tide going away', when 'the primal embrace' is torn apart:

... Rangi and Papa existed in close and loving embrace until a spirit without origin forced them asunder. His name was Rangi-tokona, Sky-propper, and he corresponds with the Tui-tee-langi of Samoan myth. Rangi-tokona first politely requested Rangi and Papa to separate but they refused. Then he lifted Rangi higher and higher by means of magical incantations and propped him up on ten pillars which he placed one on top of the other so that they formed a single, long support. Then for the first time light shone in upon the earth ...

A wordplay between hopu and hupe(e) is possible, and in Marquesan hopu means 'to embrace':

2. The cycle of ebb and high tide is governed by Moon, and twice in a day her water is flowing in and out, as if breathing. When she is straight above or straight down it is the time of flood, her water follows her. This means the times when water recedes are connected with Moon at the horizon in the west or at the horizon in the east.

Picture from Wikipedia where it is stated that Moon returns to the same place in the sky after about 24 hours and 50 minutes, which means the tidal period will be half as long (12 hours and 25 minutes):

Yesterday evening I happened to learn from the Life series on TV that in the extreme south of Africa there are baboons who are living in a tough environment with scarce food resources. They had learned that at the time of spring flood (about every fortnight) it was possible, when the sea was drawing back, to go out among the kelp otherwise inaccessible in order to search for sharks' eggs, a very nutricient food.

I remembered from ika hiku: ... Mermaid's purses (also known as Devil's Purses) are the egg cases of skates, sharks and rays. They are among the common objects which are washed up by the sea. Because they are lightweight, they are often found at the furthest point of the high tide. The eggcases that wash up on beaches are usually empty, the young fish having already hatched out ...

The 'living purses' are far out, but the empty ones are high up on the beach. This makes the image of a shark's egg useful as a symbol which easily can be changed from living (with 'legs') to dead (without 'legs'). We should keep this possibility in mind when trying to understand such glyphs as for instance:

The peculiar idea of chiefs being 'sharks who walk on land' fits with finding empty cases high up on the beach, the inhabitants evidently having moved inlands.

 

3. With Moon governing not only the tides but also time in general, it is not strange to count time in doublemonths. Waxing and waning should occur twice also in the 'her longer day', the month (her ordinary day being 24 hours and 50 minutes). Such must be inferred from the theory of correspondences.

Maybe, therefore, hupee can occur in 2 different locations in a calendar for the year - or in any type of calendar for that matter. A diurnal pattern is in harmony with the for us now civilized people foreign view of 2 'years' in a year, a 'summer year' and a 'winter year'. But each year evidently has one 'ebb' period and one period of 'high tide' (or in agricultural terms one season 'in leaf' and one 'in straw'). A semidiurnal pattern would be more appropriate for people living by the sea and Moon is needed whenever time is to be counted.

At the number of the beast, on the front side of the Tahua tablet, the 'deluge' will from our new perspective not necessarily be a description of an 'inundation' in the sky (the region of 'earth' sinking down into 'water' due to the undulation of the sky dome), nor a reflection of old stories about how the Nile - or some other great river - regularly is flowing over its banks, nor of memories of monsoon rains in some ancient homeland (cfr at maitaki):

Aa6-64	Aa6-65	Aa6-66	Aa6-67	Aa6-68

Quite possibly the origin lies much earlier, when man like the baboons of South Africa learned the value of keeping in touch with time in order to find food on the exposed tidal flats.

The connection between tides and Moon was in Polynesia evidently encoded by her 'face' (a reflection of where the sun is) and when / where Moon is to be seen in the sky. Sun and earth are the determining factors. Together they define the moon. But seen from the other direction Moon rules over Sun and also what happens down on Earth, which of course is a more practical and commonsense view.

An example is offered by the Hawaiian Moon calendar (cfr at marama) where the tides are of central importance, for instance:

... On the evening of Hilo there is a low tide until morning. On this night the women fished by hand (in the pools left by the receding sea) and the men went torch fishing. It was a calm night, no tide until morning. It was a warm night without puffs of wind; on the river-banks people caught goby fish by hand and shrimps in hand-nets in the warm water. Thus passed the famous night of Hilo. During the day, the sea rose washing up on the sand, and returned to its old bed, and the water was rough ...

We should here notice, though, that in the night of Hilo the water was warm, which does not agree with how Bishop Jaussen explained hupee, viz. as 'rhume, air froide'. Also 'mucus from the nose' and 'night-dew' give associations to a chilly environment.