I know the 4wd and fwd tanks are different, but does coupe tank fit a hatch?

No - due to the shorter wheelbase only a hatch tank will fit in a hatch body. They are several gallons smaller.

 

GD

11.9 gallon hatch tank

14.5 on the other 4wd's

 

might be a good time to do what it takes to get a fuel cell mounted up.

I always wanted to do a saddle tank like Land Cruisers and safari guys have for one of these cars. Probably just too expensive though.