Love these discussions. Lol.
Im 22, first truck i owned was a 97 f-150 2wd. It was great as a first vehicle. It towed a u haul trailer with my grandfathers 29 model a on it plus a bed full of parts. Good thing the mto didnt see us... It wasnt great for hauling. Had a load of dirt in the bed and in a 6x8 trailer, made it very light in the front end...
Second truck was my 99 ram 2500 diesel. Still have it. Has a 1 ton rear end (single wheel, with a duallys suspension) i swear, you hit bumps, feels like the axle is bolted directly to the frame. BUT it handles lots of weight. Iv had my 18ft trailer with an f150 on the rear. F150 was apprx. 4500lbs and the trailer is just under a ton (beefy trailer. Thick thick metal frame) the rear end didnt sag an inch. Iv had well over a ton of bricks in the bed, that made it sag, but barely.
If i where you, id beef up the suspension. Dont even need to replace them, just add a leaf or two. But be prepared for a rough ride when not towing. You know your truck, all its quirks and what not. Just build it up.
If you want to upgrade, maybe i can help the diesel/gas issue. Iv owned both. Diesel is much better on fuel when hauling loads. The f150 was cheap on parts, but it broke down alot. (it was a ford after all) the ram, didnt break as often. But when it did, this is what it was like.
Wheel bearing $350 vs 200 something for gasser.
Hanger bearing $150 vs 40 for gasser
Injection pump 1500 bucks for new. Got one for 500 used.
IF you maintain them, and do the research and understand how they work, they wont break as often. My mistake, i was stupid and young. Didnt maintain properly and took it offroad ever weekend, and didnt look into how they worked. The injection pump failure could have been avoided if I just would have replaced the stock lift pump with an aftermarket. Starved the injection pump and it burned out (the fuel cools it and lubricates it)
Based on your situation and type of work, id stick with a gasser. Doesnt soumd like you haul lots of weight, so i would just beef up the rear end. Maybe replace the whole rear end with one out of a 2500, if possible.
Hope my rant helps! LOL