My $.02 worth:
1) I have yet to find a chemical stripper that works satisfactorily. Now I use a heat gun and scraper - it is not hard to keep from scorching. But best is to avoid stripping altogether.
2) Removing the staining will be harder than you think. Teak cleaner is very difficult to control unless you use it on everything. Other techniques require lots of experience to get right. Water stains at least are honest and not out of place on a boat - do you really need to clean them? You might end up with a cleaned spot just as noticeable as the water stain.
3) You might be surprised how much sunlight gets below in a boat. I used interior varnish below and regret it. Lots of fading.
4) Double check the thickness of the veneer that is applied to the plywood. It is very easy to go through it with a power sander.
5) Do you really need the epoxy? How long did the original finish last? Would you be satisfied if the new one lasted that long? It would simplify the job a lot to just refinish (sand and recoat with varnish).