Chris, good to see you posting again. I have a Lance 845 on a long bed Chevy DRW crew cab and it works great for us. As you no doubt know, the CG to axle stays the sane on either a short bed or long using the 845. I built a plywood box to fit in the 18 inch space between the back of the truck and front of the TC. The extra storage room is great as the 845 has little or no outside storage. Because this 845 has a generator, I have zero outside storage where my previous 845 didn't have a generator so it had that space for storage.
We are currently in West Virginia camping, and the extra room for junk is great. Use it to store our lawn chairs, bagged, tool box, water hoses, 30 amp extension cords, water jugs, food items, fake fire logs, fire tools, etc.
You can go to my web site below, then click on Alaska trip June July of 2004, 2006, etc., then scroll down toward the bottom of the page, then click on web storage photos, to see what I built and use. If I do it over, I would extend it to come out over both side bed rails. I keep thinking about having one of the local boat shops in Stuart build me a fiberglass box that would look better. But a lot more dollars involved in that. LOL