I feed my pups on the tailgate. Put an ice chest or something next to it to give them a boost until they are big enough to make the jump. The truck bed needs to be a good experience for them to the point they look forward to it.
Sounds like a good idea to me.....not much different then conditioning them to a particular noise before feeding. (makes it 100000x's easier to call em outta the woods....imo)
"the sun is shining somewhere in texas" -Jason Boland