I'm in a similar situation as you too. I just ordered an AF 811 that will be ready for me the first part of January.
I had a Lance 650 (the lightest hard side with all the amenities, about 2,500 lbs loaded) on a Ram 3500 short bed with no suspension upgrades. Now that I know I'll be somewhere around the 4,000 mark I realized I'd need to beef the truck up.
Seems everyone is in agreement that tires are the weakest link. I, like you, had E rated tires rated to 3,640 each. I could have opted to go to the 4,000 rated tires but instead jumped to the Vision 19.5 wheels with Toyo 920A's. Now I'm rated to 4,500 pounds with a 14 ply tire. Obviously its great to increase each tire almost 1,000 pounds, but for me peace of mind was important. It was costly, but consider the total investment......truck + camper + gear. New wheels/tires is a somewhat small percentage.
I also opted to do Firestone Airbags and lower Stableloads. My hope is to have both adjusted so they work together. I'm a firm believer that you need to use your suspension and not just have the weight sitting on two over inflated balls (airbags).
Lastly, I added the Hellwig sway bar. It's beefy!
So in the end I'm sure my stock wheels/tires would have gotten the job done. However, I plan to put many miles on the truck/camper combination and as mentioned earlier, peace of mind is so important to me. My travel will include fishing and hunting, which brings in boat ramps, gravel roads, dirt roads, etc. A good tire is key. Oh, and another thing.....the Toyo 920A's have the "mountain snowflake" symbol. I wanted a good winter traction tire. We both basically will encounter the same roads and weather so I'm sure you can relate.
PM me if you want photos or pricing details on my wheels/tires. I opted to go with Les Schwab. Yes, I paid more.....about $400-$500 for the package, but it was worth them dealing with everything. Valve stems (TPMS) can be challenge and now that they did everything I know I can go back and they will take care of any issues. My other option was to order online and then have a local shop install. Don't forget that these are not normal passenger or light truck tires. All shops won't install......most can't.
One more thing. I've only had the tires for a few days, maybe 75 total miles. They are a little "squirmy", but not too bad. I hear they will settle in. The ride is slightly (like I can hardly tell the difference) more firm, but honestly my 3500 rides really rough anyway. The day I drove it off the lot it was stiff. I just feel this is part of the deal. If you want a truck with a lot of payload then by nature it will be stiff unloaded.
Good luck and I know you made a good choice with the 811. After my research, the 811 was the clear winner for what I need.