Bob - very nice truck - I had the 98 F150 OffRoad Extended cab with the 4.6 and a 5 speed - great truck that I ordered from the factory the way I wanted it (til my wife made me get a "Family Car")...
If you get the bedliner, the fit well under the rail caps that Ford puts on the XLTs and better, very slick and unobtrusive layout. You should at minimum get that and if the install it correctly, it will not scratch the bed below.
A cap would be nice but get it if you plan to use it. Now for surf fishing, you could roll a sleeping bag on an air matress and make long surfcasting trips peasurable
. For surf rods, you hang internal rod holders and run the tips through the rear slider - can manage 10' rods easily inside the truck which really is easier than external.
They are kind of pain to remove solo but you can make up a jig to help you do that if you need to.