Hi, we're in the same boat - same age too! Sometimes he'll get back to sleep eventually after shh/pat, I've also had it suggested to me that we could try EASAS - ie a short A time after the first short S, before going back for another S - but this hasn't worked for me yet. So we usually end up with a period of trying to re-settle, then often giving up, say, 15mins before the earliest I'd next feed him, and let him sit in his chair or mat before the next feed. This works quite well as I'm trying to keep him upright after feeds, so having that A time before the feed at least gives him some tummy time etc - but I'm getting off track!
One thing that I have found really good is to AP one nap a day in the sling, where possible - this gets us both out, gets some errands done and ensures DS has at least one decent nap and doesn't get too OT!
Another thing that's sometimes happened, although kind of unintentionally and I'm sure many people here would disagree... if he's had a long time trying to resettle from a previous nap, I sometimes let him fall asleep during the next feed, for 30-45mins. Then we have A time, and then there's time for another 45min nap before the next feed. This is definitely Plan B/C/D (!) but has sometimes worked to break the OT cycle. Now I have a feeling that in a few weeks, maybe when we're trying to initiate a 4h EASY, it would be better in the long run to be consistent with PU/PD and routine and not use this trick, but I'm hoping it won't do any long term harm right now - will be interesting to see what advice you get from those with more experience!