Make sure you have to be selective too on the JAV you translate like, if the JAV all about straight sex from the beginning then pointless. Pick a JAV with some story like maybe some Female Detective or Female teacher series or whatever series which has story aside from sex.
Totally agree - it's often the situation in which the female character finds herself and her reaction to it that's so sexy, and translation is needed to do that. Translating "Oh my God, it's so big!" 100 times is a total waste of time.
My other strong advice would be to use automated tools to get your translator started quickly. Produce Japanese subs using automation as a first step. This will take minutes and give you a good (and hopefully accurate) framework of timings for your translator. You yourself (or anyone with an interest) could then tidy up and fill in the automatically generated file (music, etc. prevents a lot being captured). Only once you have got a decent set of Japanese subs do you need to get your translator involved, making the whole process more productive (different people can be working on different projects at the same time) and keeping costs down.
If you do go down this route, make the Japanese subs available alongside the translations. This will allow the community to identify any problems with the process, suggest improved translations, and also potentially enable further translations into other languages.
You could find yourself with a success on your hands if you make the right choices, and I would be willing to invest subject to seeing the end product (like others).
Good luck!