

If they're light enough to manhandle into position, they're too light to give any significant level of protection, whether metal or fibreglass.
If they're fibreglass, the flamethrower is more dangerous to it & the crew than to the enemy.
Reload time of the 105mm recoilless will be negatively impacted by the "flexible stainless steel tube", which, when it starts leaking propellant gasses into the "turret" pillbox, will severely hamper crew effectiveness.
The thing is, for all intents & purposes, a three-man coffin-come-crematorium.
