Lock the RV, bikes and a generator. Storing the generator is best. The grill and chairs don't need locks. The majority of RVers are honest. The other few - well, worrying about everything will drive you nuts.
In 16 years of full-timing and traveling constantly mostly in public parks and boondocking on national forest and BLM lands, we've never had any security issues. Never heard of anything from our full-timing friends either.
Generators are a prime target however. Ours was built in so didn't have that problem.