So I was hoping to get some expert input on a possible new potty training tactic... And this post got out of hand in a hurry, sorry for the length!

A little background - this particular dcb is 3.3 years old, parents just started potty training (we're in week 3), though he's been in pull-ups (or as I like to call them, diapers ) since February. The approach we've taken is pretty much the standard we take you, you go - get a candy, you don't go - try again next time. It's going fairly well and he's completely independent in the routine (aside from some help getting re-dressed and washing hands), so I feel like he should be starting to go independently or at least tell me when he needs to go. He is also generally dry after nap, so I know he can go at least 2-3 hours without "going."

Two problems
1) He doesn't tell me when he needs to go, I don't think he gets the sensation of urgency, or being wet, because he's always been in something that would pull the moisture away. He'll also tell me that he's dry when he's not, and has told me he pooped when he hasn't (when I asked him if he pooped). I've been trying to encourage parents to do the underwear-under-pullup thing but they don't seem into it...
2) If I put him on the potty he usually always produces something and gets a reward, which in itself is fine. But I will have him go and then go back on a half hour later (I usually do it before we eat, before we go outside, and before nap - sometimes these are close together) and he's gone in his pull-up and will go again in the potty just a bit... and is then rewarded again.

I'm considering starting to reward him for having dry pants, rather than simply going on the potty. I'd never try this with an early trainer, but I feel like at his age he'd be able to get it, and if not than at least we'd have some more information about his abilities. Has anyone tried this? Would you recommend it or no? Does anyone have anything else they might have tried that you think might be more effective?

*Side note:I'd also like to reward him for asking to go or going independently, but feel kind of like it might be a sticking point with him - he's very much babied at home, and needs to be led to any and all activities or will ask permission. I think it's going to be an obstacle for him to learn to do this independently so trying for dry bum first might be a better transition for him.*