Not quite sure what you're proposing.
Yes, mofsets, RAM, etc will produce heat, but the FC77 & plexi-glass will take care of that. Lots of people have used open fish tanks with vegy oil (for silent computing) and the glass + oil surface seem to transfer a good 50w of heat away without any extra help. Plexi wouldn't be quite as good, but enough for m/b only heat. If you don't insulate the cold side of your TECs, this will cool the oil anyway.
Don't submerge your h/drives, and make sure you string your cables at least 1m above the tank. Less, and after 6m you'll have expensive oil dribbling out of your mouse and any other USB stuff.
It's all been done before- just use your head & follow the above tips! I'd use a sealed tank with external rads because the FC77 will evaporate slightly faster than water if you don't. :-(
PS. Most fans still work submerged in oil for a very long time (amazingly) so don't be afraid to add one for circulation if needed.
PPS
Here's a link to some bored guy using FC40 & LN for a bit of fun. You could do better for long term use.