Curious if you are buying the camper new or used? The dealer I just purchased my new camper from did the tork-lift tie-downs, super hitch/truss and wiring install at no extra charge. Purchasing used may be different though. I installed the tork-lift tie-downs and super hitch on the previous truck I owned, it took the good part of an afternoon but it wasn't that hard.
If they're willing to charge that much I wonder where else they are willing/trying to rip you off? Take a good look at the deal before you sign on the bottom line.
For the camper plug I have always just ran an extension from the 7-pin bumper plug. I don't use that plug-in for anything because I don't tow a heavy trailer and if I did I would just get a splitter adapter and still do it from there rather than trying to splice into the trucks wiring and drill holes in my bed.