I've looked at Radio Shack, Harobr Freight and JC whitney for a
solution to a project: I'd like to be able to recharge the camper's
batteries while plugged into 120VAC.

This would require wiring in some kind of charger from the electrical
box(es) inside the low cabinet to take off 120VAC from the utilities
connection, and service 12VDC to somewhere that makes sense on the
wiring harness.

It would need to shut itself off automatically when full charge was
reached.

Ive found this at jcwhitney.com

http://www.jcwhitney.com/webapp/wcs/stores/servlet/
ProductDisplay?productId=7168&catalogId=10101&langId=-1&storeId=10101

but it's $100.

Any other suggestions? Seems such a waste to pay for or otherwise get a
connection to AC then not be able to charge the batteries while out on
bikes for a couple of days.

Jim