I have a 22 3500 SRW with the SO that I got early February this year. I was initially looking for a HO but after seeing the failures for the late 22's and early 23's I went with the SO. (My previous trucks were SO's so I knew what to expect.) The primary use for this truck is to haul travel trailers. To date, I have towed over two dozen different trailers ranging from a small 3000 lb boat to a 43' park model that weighed 11,600 lbs. I towed the park model from IN to Western WA. Fuel milage with that one was abysmal. The truck just hit 27k miles today with about 12k of that towing. Most of that towing has been in the mountainous regions of WA, OR, ID and MT. So far so good. However, for what I do, my next truck will probably have the HO.
I was at a local Pilot travel center the other day and two Rams pulled in, both with diesels, and both towing 5th wheels. Both deliver trailers for a living like you. One was a 2500 short bed with the SO, the other a 3500 long bed HO. I know there is no way the 2500 was within payload capacity, regardless, the guy said he has towed everywhere without issues. The 3500 driver said the same thing.
I have read through so many different threads, forums and watched videos. I realize that in stock form I most likely won't have any issues with either HO or SO. I also came to the conclusion that the SO would serve my purpose of towing a 5th wheel a couple times a year and being a daily driver the rest of the year just fine. However, I always like to error on the side of safety and for those "in case" scenarios, I will most likely buy the HO.
Also from what I've read, fuel mileage differences will be negligible. I am doing it for the benefit of the transmission. I wish I could get a truck with the SO and Aisin without going to a chassis cab, but that can't be done.