HY,
I have a Bigfoot 2500 4000lbs with a 2005 Ram 3500 DRW. I like my DRW, 75 mph on highway all day nice comfortable ride no vibrations. I had it 2 years on 19.5 alcoa singles ride was like on bricks and with lost mph due to heavy tires.
offroad with the camper ( had a lighter Bigfoot 1500 before for offroad) DRW is more safe due to swing. more traction with the DRW.
the only place whe is better SRW is in places where we absolutely need to follow deep tracks
My observations for offroad with Bigfoot 1500
trucks are very heavy, put a camper on it is worst for offroad. soft sand or soft mud and we are stuck due to the weight. a lot of swing anyway.
engine: these trucks are made to tow or haul at high speeds not for crawling at 5-10 mph. because of the turbo the EGT are going through the roof after a while( maybe less with the 550/5500 due to a gearing suitable for high loads) we need electric fans to push a lot of air through the radiator and intercooler at slow speed not belt driven one like the Dodge ram 3500. a better intercooler and a better oil radiator to cool the engine a lot.
transmission: same for thansmisson, bought on ebay a transmission auxiliary cooler with fan and thermostat 170 off 180F on.
suspension needs a lot of work
brakes need to have exhaust brakes and aloso 4500 5500/550 has better brakes huge pistons and discs.
at 100 000k Can dollar for a truck I'll not abuse it offroad, unless you have a money pit.before the trucks were easy to repair, today is a nightmare., too much electronics, sensors, engines are too sensitive to overheating. Overheating will makes things worst, triggering codes melting sensors, wires etc.
So if you want offroading a 5500/550 is suitable due to gearing, brakes, do what you can to prevent overheating engine, brakes transmission etc. or an older truck which is a lot more tuff not so sensitive to overheating. Also the lightest camper I'll be comfortable with to minimise load.
At last I'll worry about SRW or DRW. But If I was me I'll keep it DRW all day long. Offroading in Colorado and Utah never a single time I've thought I'll be better with singles