"he now does a capped 30mins nap in the morning and a 1.5 - 2hr nap after lunch (about 1) which has been working really well."
That's actually really good compared to my DD...
I don't have any good suggestions but just wanted to offer my support and share my experience. My 7 month old DD is in daycare 5 days a week (full time). Like your LO, she is a very sensitive sleeper, so on a typical day, she'll manage three 30-40 minutes naps. On a good day, one of those naps may be 1 hour. She tends to be a 10/10.5 hour sleeper overnight so EBT is also out of the question. However some days, it's just so bad that I end up putting her to bed 30 minutes earlier, which means an extra EW. Fortunately, on these extra EW, my husband would give her a bottle and while he gets ready for the day, she'll take a short 30 minute catnap before beginning her day.
On weekends, she'll make up by giving me two 2 hour naps. Of course that is in her dark and very quiet room. If we're out and about, forget it. It's back to 40 minute naps. Fortunately she copes fairly well with short naps most of the time (I think she's mostly angel/textbook - very easy going and mellow.) And so far, her nights have been good, with the occasional 3 AM chatting to herself.
I used to stress out so much about this, but becoming more relaxed because I have to work and have no other choice but to put her in daycare. Hugs... I do think it gets easily once they get to one nap (ie. toddlers at DD's daycare have a dedicated nap period when it's much quieter).