I thought about it a little and if you still want green I would go with 2 SST-90's
If you afraid working with bare emitters and can't find them mounted on board maybe you can ask Nailbender. He
sells P60 drop-ins. Green SST-90 is on his availability list. Maybe he will sell you just LEDs mounted on board.
For a driver I would assume you want a switch on the boat not in the water with light head.
It means that H6Flex need to be also out of the water (you can't have long wires between switch and driver). You will need extra box close to power source to hold switch and driver.
H6CC is simpler and can be operated just by turning power off and on (and be installed in the head). With simple power off and on you will lose dimming but if you really need that you could use 4 wires for connection between head and boat, two for power and two for connecting external pot. I believe Der Wichtel driver will work the same but I never used one (you need adjustable version if you want dimming).
For housing just machine it from aluminum ("just machine"
I wish I could do that, access to CNC is very helpful here
). Salt water will not corrode aluminum but you can anodize it for extra protection. Most aluminum corrosion close to salt water is caused by galvanic corrosion since salt water is electrolyte.
You should avoid mixing dissimilar metals on housing (like do not add stainless steel screws to aluminum housing, use aluminum screws). I don't really know how important it is in this case but I would think you will keep these lights in water for prolonged times.
For lens I would get polycarbonate. You don't need it very thick since it is not for diving but you want it stiff enough, I would not go lower than 1/8 in and given small price difference I would go thicker. You can buy nice AR coated polycarbonate
here. Glass is good but is brittle while polycarbonate you can hit with a hammer.
See lights
Betti or
Packhorse (and others in diving forum) made for ideas about housing. Agro cable gland they used is very good. It is nickel plated brass. There is a potential of galvanic corrosion between it and aluminum but I don't really know if this is anything to worry about. If you want you can use some Delrin as Betti did (just make sure there is enough aluminum exposed for transfering heat to water) or look for plastic gland.
Agro glands and some cable you can buy from
350xfire.
