Effectively covering that back-of-the-lid part is not looking like it can be done. I suspect that if the gasket does not go all the way around the tank then the overall effectiveness will be greatly diminished. Additionally, the gasket will need to fit nicely like it does on the old Rinse Station lid. However even my old Rinse Station loses IPA over time at about 100 ml per year.
I think Formlabs statement that, their prototype gaskets did little to stop the evaporation, is our clue that this is a unsolvable problem given the cost limitations of such a product. A very thick tank that has a clamp seal is not an easy thing to make.
Some people have pointed out that they are cleaning parts all day long every day and that is consuming lots of IPA as well. Be that as it may, there are some of us that print only a few times a week and we are loosing 90% of our IPA to evaporation from the Form Wash tank. I have measured it and it is about .5" lower after just three weeks.
This is the link to the other thread on this issue: