Don't know how wide your steps are but Harbor Freight has a folding aluminum stool for about $20. Very lightweight and sturdy, and about 24" long. I bought one and shortened the legs on it to make a step so my Mom could get up in my truck on the rare occasions that she rides along. All you need to do is drill out the rivets holding the feet on, cut the legs to the desired length, stuff the feet back on, drill new holes, and pop rivet them back in place.
But first, I would be going back to the dealer and saying, "Hey what's the deal?" Unless you have a ridiculous lift kit and oversize tires on your truck there is no reason the stock steps should not allow access. It's a brand new camper on a 2 year old truck. If anything trucks have only gotten HIGHER in the last two years.
Putting 10-ply tires on half ton trucks since aught-four.