partial cosleeping while nightweaning, how to transition to cot fulltime again?

Hi,
This week DH and I decided to nightwean our nearly 8 mo DS in an effort to 1) try to get my cycle back so we can TTC #2, 2) trying to get DS to wake up less during the night as he was after the boob every 2 hrs.

The nightweaning has succeeded brilliantly as DS is not even asking for boob anymore. The downside is that during the nightweaning to make it easier on DS and myself I have had to resort to partial co sleeping because DH was away for the night for work and I was so exhausted. DS is sleeping so much better though, wakes up once around midnight maybe, then for the rest of the night sleeps till 6 am ish when I will BF him. Now that DH is back home I have to send him to the guest room once DS wakes up but this is not ideal for us and we really dont want to have DS fall into bad sleep habits by expecting to sleep near me at night. He falls asleep by himself in the cot during the day and also the first stretch of the night. just not the second part of the night. how can i transition him back to the cot full time easily without CIO?

Last night I tried it, gave him cuddles and he nearly fell asleep in my arms in the rocking chair in his room. then i tried to put him down in his cot again, his eyes wide open obviously. I turned him back on his side and again he nearly fell back asleep, he turns on his back and bam eyes open again, little bit of whinging. this went on for about an hour or so till he was so tired he started crying loudly. I gave in after that hour because I was so tired myself and I cant see myself hovering over the cot all night. He ended up tossing and turning for another hour after that in our bed while DH was in the guest room. After that DS slept until 6 am.
I have to add that I am using a Safe T Sleep because I dont like the idea of him tossing around his cot at night time, he bumps his head on the cot sides if i dont put him in it and once he's on his tummy he is wide awake. I have managed to teach him to turn on his side in the Safe T sleep but he still wakes up once he turns on his back again

With getting back to sleep at night I used to stand next to the cot and sing quietly and pat/rub until they went to sleep. The first time it would take an hour to get them to sleep, they weren't crying in that time just not sleeping LOL! Next night it was generally be 15 minutes, then 5. It gets to be more about the sleep cues of singing and patting than anything else. Obviously different kids respond to things differently....DD1 was much more about singing and it worked really well, but when she got a tooth or was sick she'd get out of whack (sleeping in our bed for the worst nights) and once she was recovered she would 'forget' the cues and we'd start from scratch all over again every.single.time! DD2, on the other hand got over stimulated with too much singing and patting and hates rubbing so the cues had to be more subtle but as soon as the pain/sickness was gone she would be back to sleeping through without me having to do anything.

I'd say try a few different things on for size and don't necessarily disreguard something if it takes s long time the first night, it might just be a stepping stone to forming a quicker easier habit.