Yes, 3hr may be a bit much, but sounds like wake to sleep or hold through the jolts might help him learn to get through that stage of sleep that he's clearly struggling with - I'd probably try hold through the jolts first for a week and then if he's still not extending his naps, try W2S at 20min - I think its probably worth a try, though it can backfire.
Are you reducing the next A time at all after the 30min nap?