a quick question

There's no requirement to unhook a set before fueling. That would be a Fedex requirement and may be just a local terminal requirement.

Be extremely careful what you hook up to your truck. Be sure you do it right or you can find yourself in a spot you'll regret. I've always gone to the company so they know. When I hauled gasoline the company was so resertictive on what could go into the truck they made the drivers used the company's mechanic to even hook a CB up. Of course they had reasons.

 

Don't know about the FedEx thing. King Pin locks are like any kind of lock, "they keep honest people honest" The cheap steel ones in most TS are pretty flimsy, I have one called "the enforcer" and it's pretty heavy duty, but I have seen a repo man in Chicago take one of them off in about 5 mins. So don't put too much faith in them.
As far as an inverter you will probably want about a 2000 watt output minimum, for a microwave and fridge. Most companies won't allow you to install your inverter yourself. They will charge you a pretty health fee to wire your tractor and then you supply the inverter.