Howdy folks!

I have a little bit crazy idea and i need some help and advice. Im planning to buy a 04-05 f-150/5.4 triton4x4 and put 4 seats in the bed. Regular sport seats from ebay 2 in a row, 2 rows total. What i wanna do with the truck is take it to the mountains with 8 people on board driving up and down on dirt roads (no insane grades) with little mud (not deeper then 10-15 inches), rocks, crossing shallow creeks and stuff. What i d like to know is what modifications i should do to make the truck dependable and very stable, also i guess im gonna need some protection to protect the truck from damage caused by rocks.
Budget is around 5k but if you guys just tell me what to get and do i ll be still happy!
Thanks for the help!