[/quote]

we get dinged for Lexan/plastic $X per cubic inches/feet. We are close to the $500 limit now. Once we see how much room we have after our mods are added up. We should have room for the rear hatch. [/quote]

If this is for ChumpCar, check the rulebook for 2015 updates - Lexan rear windows (including hatch) are now free so long as they conform to the OE size, shape, and location. See Rule 9.1.6.3 and Rule 9.1.7.1 here