Did you mean AK2612? Is it either or? I mean is it a Toy Hauler VS a Diamondback ATV Rack? Will you be pulling a trailer if you have the Diamondback ATV rack? Do you need a Toy Hauler plus the ATV rack?
I can't give you any advise on the F150 I think you would know best on what your truck can do. Having said that, if you do upgrade I would consider going with a one ton vs 3/4 ton Especially if your planning on carrying two ATV's on the truck and pulling a Toy Hauler at the same time..
I have had several Toy Haulers. I did have a Rack Lift system made by Rampage to drag my Harley in the back of the truck for a while in between Toy Haulers and I hated having my bike out in the weather. the system worked OK but it's much easier to load the bike in the back of a Toy Hauler vs loading in the back of a truck.
If you decide to go Toy Hauler I would consider a enclosed garage model. It's nice to keep the bike, mud, dirt and sand in the garage away from the living space. The garage does make a great extended living space (man cave)when the bikes are out...