Welcome to the forum,
This is only a suggestion, Have you given any consideration to putting your equipment on a small trailer? This would free up your pick/up bed and make more room for more equipment, and you could drop the trailer in the back yard without having to unload it after each job. I'm sure some small angle(L1x1x1/8) would frame up nicely to house your tanks and generator. Lockable tool boxes would also help keep tools that would walk off safer too. I've had an 87' S10 that I bought with less than 1500 miles on it. I pulled the four banger out and dropped in a 350 w/ a 4 speed automatic with in the first six months. It made for a nice truck to "haul the mail" in. If you still plan to put all this equipment in your pick/up bed, just keep your framework light so you can haul more equipment without putting too much burden on your truck. I've built too heavy before and paid for it in the mountains. Those little chevys are great trucks and will be around to give you good service. Keep posted, because there are alot of people with good ideas that monitor this forum and can add their two cents that may work better for you. The more ideas the better, then you can decide which ones you may want to use.
John Wright