I wouldn't be worried about the collar. The diameter of the collar isn't large enough to have any rotating mass that would cause vibrations or anything to loosen the bolts if torqued properly and locktite is used. There's no end thrust applied to move the collar forward so that's not an issue either. If your really worried about it coming apart, assemble it, tighten the collar in place and then remove the drive and tack the two pieces of the collar together. I'm not a fan of doing something like that but it would give you the peace of mind you looking for.