I am on my 4th truck pulling 5th wheels and always carried all my tools in the truck. I also use my truck in the summer season for my business and the box has to be free of any added boxes. The floor is all natural and the floor has never shown excessive wear and tear. I hate to have to clean rough surfaces, so the smooth finish suites me well and liners are to slippery for my need.
I have a 20Gallons extra tank against the front box wall that only takes 5 in, and can be removed in 15 minutes if emptied.
I bought 2 identicle in rail height truck boxes with identical keys and cut one down to be installed behind the V notched tailgate, that I made super heavy that I can use, I put all my mechanical tools in the lower rear box and the Kayaking equipment in the front full height box.
The 5th wheel fits between the boxes and only put heavy stuff there while traveling, and in 18 years never lost anything in that location, so I don't see the need of a soft cover that any one that wants to see what I have valuable there can cut the soft topwith a knife. Have you seen the knives the carry these days, I have convertible cars and never leave anything valuable inside so my tops never get ripped.
I have made all my racks on the trailer and the truck and they are heavy duty and made not to fail.
This fall we came down to Florida with the 16ft tandum kayak sitting on top of the cab in front of the Big Country and it was a blessin as it was the cheapest wind deflector I have ever used as it acted like one and saved a lot on fuel mileage.
Of course my truck is a summer work horse and set up so it can be both the towrig and the worker. And in some 15 minutes can be converted. Yes I use side racks on the truck in the summer, something I never seen on a pickup for years, and I get lots of comment about them. Its so unpracticle to have an 8 ft box that can only hold 21 inches of stuff, and the sides get all scrached if not using racks. I usualy load to above the cab when the truck works.