Ah, here's somthing similar to what I was thinking.
E-wheel for any vehicle - MIMA Honda Insight Modified Integrated Motor Assist
Perhaps a chunk of motorcycle might work well?
Tucking under the back of the truck would help with the swivel/steering issue. I'm just tossing some ideas out there.
A while back, I was thinking about converting my S10 to hybrid electric, but there are a lot of little things that can make it problematic.
I like the concept of an EV trailer, but electric is best for in town and slow speeds - times when I would rather NOT be towing a trailer around!
A smaller device that could mount on the truck and still be easily removable when not needed would be a great experiment.