mgr you da man! 
I totally agree with the left Gauntlet being the easy one (and probably the best place to start). Now when I held this up to a Gauntlet for sizing though, I was using the right one (GA). It will not fit inside the small piece that attaches to the side, but it MAY fit inside the right Gauntlet housing itself and eject at a slight angle outward between the main Gauntlet housing and side piece.
I'm with MMM...it really comes down to measurements.
How much space is in the left gauntlet flamethrower case?
How much space is in the right gauntlet beside the arm (on the outer edge)?
LxWxH= a definite answer of how it can be done
If anyone takes these measurements, please specify which Gauntlets you are using and take internal measurements, not external.