Hi Louis,
I've been wondering where you were, had not seen a post recently. I might have missed it.
After watching you're fantastic conversion of the M5, I'm hoping the "35 RC Tank" conversion will make it a bit easier. That will not however addressee the fragility issues and concerns.
My goal is to convert one of the M5s to an M3. That will prove to be challenging so I hope the conversion set will ease some of the "pain"!

I can see that the motor/gearbox installation will need modification as the slope of the glacis plate is very different than the M5. It is good to see that converting the turret to the rounded M3 style will not affect their design on the turret electronic/mechanical fit, I hope!
I "plan" on converting my second M5 kit to a M4 High Speed Tractor.
Barry