My thinking is to go with a shorter acting drug which would get him through the procedure, but wouldn't have him zonked the rest of the day. If his pain isn't a constant issue, then this could work.
Depending on what he weighed, you could try Actiq. It's a transmucosal form of Fentanyl which would have a pretty rapid onset. My holdback on this drug is that it starts it's dosing range at 200mcg and (as I said, depending on his weight) could readily send him on the road to CS, or deeper into sleep.
If we can't get the fentanyl dose low enough to do the trick, I would suggest Dilaudid LIQ. While MS LIQ would also do the trick here, Dilaudid would be a little better punch for severe pain I am sure he is having. This has a nice quick onset, and if given correctly shouldn't be too sedating.
As far as an all day control medication you're pretty much stuck with either Oxycontin or MS Contin (or another time release MS). Avinza is really good, but again the lowest dose is going to be too much. I think you're going to be looking at doing OxyIR 4/5 times a day and schedule it to where he can have a constant dose.
Finally, on Lortab. I do ALOT of pain management and I REALLY like Lortab. BUT... It is almost useless alone. Minor issues will be covered by it, but for anything severe at all, you're going to need stronger. However, when needing a PRN in combination with Methadone (AND Methadone would be GREAT in this case, but I've just never seen it used in kids) or MS Contin... you get GREAT results.
Sorry I couldn't be more help. I don't a huge amount of PEDS pain management. My knowledge mainly applies to adults