Does the tank compartment also have to be fuel proofed, or just the firewall and engine area?

Thank you.

I always fuelproof the tank area, just in case you have fuel leaking or fuel tank issues. It doesnt take much and its worth the extra time.

And... drill a hole in the belly in the fuel tank compartment. In case of a tank leak/rupture, give the fuel someplace to drip out before it gets to the tail.

Yes...go ahead and fuelproof the tank area. Never hurts.

Or...you can do like some, and use a transparent covering material....that way you can see when the fuselage is full! <G>