It may be too late now - but are you a member of the Beaver Ambassador Club? Thue have Gillig parts and service manuals available for their members.
https://beaveramb.org/
Well, the name of the organization has "Motor Coach" in it - so unless a name change is also going to occur, I would say "No" to the idea.
However, I do not object to FMCA changing their name to FRVA and allowing towables.