Burping techniques for sleeping baby?

I started doing dream feeds for my LO to encourage him to sleep longer stretches in the night. So far, doing good, slept 1:30-7:30 with a short 4am snack/dream feed! But I struggle so much getting a burp because he is so sound asleep!

Last night I tried for 10 mins. Didn’t get one so I put him down. Then he squirmed in his sleep because he had a burp. Had to pick him up 3 times to try & burp him before I got one out!

The only techniques I know are over the shoulder & sitting them up. Any suggestions?

Edit: he really struggles with gas. He will squirm & grunt & be unsettled until it’s out