So, just to put a wrap on this thread for anyone who is/was watching (or might find it in the future), I ended up going decidedly low-tech for a solution.
As I noted before, because my RAM 1500 has the short box, the wife's bike and mine are about 2 inches too long to stand straight in the bed and close the gate. But, if you turn the front wheel in, they have no problem fitting. The challenge, then, became, if you want them to stand like that, how do you do it.
Basically, I built a trough, if you will - I got 2 2x4's and cut them to about 58" length. After measuring (based on the angle of the tire/wheel), I then cut a couple of 3" pieces and used these to attach the longer length's together. I then attached a large metal O-ring to each end of this construction, and subsequently connected that O-ring with a large metal carabiner-style hook to the hooks in the front of the bed.
This assembly allows me to place the front wheel of each bike between the 2x4's such that the wheel will not twist.
I then used ratchet straps on the front and back of each bike to the respective bed hooks to secure them. Laid the kids' bikes in the bed between them and voila!
I also bought and cut some lengths of grey plumbing pipe insulation (looks like a pool noodle) which I used to cover the edge of the truck bed so the bikes wouldn't rub and get scratched. These just slide on and are held firmly in place when the bike is strapped in - I do remove these when I take the bikes out so they won't blow away.
This works fine to allow us to take all the bikes, which was seeming to be a major issue. It's not perfect, I realize, because the entire bed is used up with bikes - I don't have much room for anything else, except maybe a cooler if I moved stuff around.
But, it was cheap and easy and does the trick until I find something better. I'll try to remember to take some pics and post them up here so people can see what I did, in case my description isn't clear.
2014 Coachmen Freedom Express 23BHS w/50th Anniv Package
2015 Dodge Ram Laramie 4x4, V8 Hemi w/tow package