There is a company that has been around for years and years, Voodoo FX. They can help you out.
They even can give your SEAVIEW
its PING: http://www.voodoofx.com/news.htm
As for the lighting kit, I clicked "Page Down" 17 times and there was their kit (your computer may differ.) +$60 with shipping.
I will probably get a kit from them when I get a bit ahead of the bills . . .
P.S. As for waterproofing? Maybe a good layer of clear epoxy over the connections and a good watertaight box over the electronics. I have never tried. Maybe a more experienced sub driver could help with that one.