Yes, I'm a newb, but only to this forum, got years of racing sportscars (Alfa Romeo, Corvette and McLaren). You really should not put an air cooled gas motor into a box, even with a fan to provide forced draft over the cylinder fins. Overheating is the first reason, and you know that heat is the enemy of your amp, but even a better reason is trapping flammable vapors in an enclosure. There is a very good reason that power boats have bilge fans on a timer before engine start is permitted - the reason is a very loud bang followed by a hot fire. Say it can't happen to you? True story coming up. Got a friend that tied up in a lock (Thomas J. O'Brian Lock and Dam on the Calumet River going into Lake Michigan), shut off the engines, while the lock cycled and the lock gate opened, turned the key, vapors ignited in his Carver ($$$ cabin cruiser), blew him into the lock basin, but not before 2nd degree burns on face and arms. This was an older boat, so it didn't have fan interlocks, had carbs (like all these little engines we use) not f.i., and he didn't open the access hatches to vent. I know you want to have a hot ride (we all do), just not the kind of hot that burns your rig and A$$ to a cinder!