If you want to follow all the numbers on the manufacturer warranty sticker, a minimally optioned AF990 may be able to be towed by a stripped Class 3 SRW model configured for maximum payload. Once you add a towing requirement to your combination, you will not find a SRW that will not be over at least one of those numbers. Depending on the options you choose for truck and truck camper, you may also find that that the only way to stay within all stickered numbers is driving a DRW.
In my case, the current camper I have chosen barely can be carried most modern Class 3 DRW trucks. Because I tow a heavy trailer while carrying a heavy camper, I drive a Class 5 DRW truck. My AF811 empty was over the payload sticker of my F250, but with minimal upgrades it would carry it without any issues. Once I added my trailer on the back, more expensive upgrades had to be done to make this combination reliable and safe. I researched that truck's individual pieces to find actual component manufacturers and their ratings, then I upgraded the weakest ones to bring back a safety margin and improve load handling.
Yes, if you look at heavily optioned AF1140's or 1150's, they may be too heavy for certain configurations of a Class 3 DRW if you go by the manufacturer warranty sticker.