"Charge for installation?"
If the Ford factory prep is anything like the Dodge/Ram factory prep, "install" is:
1) take hitch out of box
2) put hitch head on base
3) put unit in back of truck and twist the lock handles
No way would I "pay" extra for an install.
RV dealers should be for buying RVs only... Nothing more.. Everything else on earth can be had elsewhere for a MUCH better price. Your friend should be looking at a truck accessory store.
This:
http://www.turnoverball.com/products/rvhitch/companion-oem-5th-wheel-hitch-fits-ford-puck-system
can likely be had for $1100-$1200 or so tax included.