Classic 18mo SR hun.. We battles with it for about 6-8weeks which also coincided with the canines coming through.
Is he happy rolling around in there or is he asking for you? The reason I ask is that DD has done this since she was around 1yo and nothing I did made it any better. She's just happy winding down for the day up there. During the 18mo sR it was taking nearly an hour
. Normally I can just leave her to it and come downstairs and be on here
We did through stages recently where she was UT and needed the nap capping as she was unhappy about going to bed it seemed. Lots of call backs which drove me up the wall. But that was recently at 22mo I think?
All I can say is that once the 18mo SR stopped and teeth weren't bothering her so much, poof back to only 30mins rolling around again. Whatever I did didn't work at all. And we we getting random WU's in the night too just like you mentioned.
Your routine looks good as it is tbh. Your DH won't become a prop unless he's soothing him to sleep like rocking etc. Wi/wo are all good tools to use on an IS. I use words a lot, with encouragement from another mod on here, I sat outside DD's room when she was calling out (but not crying) and firmly told her 'it's time for sleep' over and over. Wi/wo used to rile her up.
I hope some of that helps, I find it's useful to hear others have been through it too!! ((Hugs)) xx