Towing w/out weight dist -- am I being too conservative?

see what the weight carrying limit is on the truck hitch reciever. Often it is much lower than the WD hitch limit. That may answer your question.

don't estimate tongue weight. It can easily be much higher than you think. each battery adds essentially 100% of its weight to the tongue as do any propane tanks.

If you choose no WD hitch, at least use a WD ball mount that has a ball for a friction sway control and use it.