I completely understand your dilemma and if you’re not comfortable leaving Aidan to cry or fuss, the Ferber is definitely not for you. Plus if you’re sharing a room then the Ferber technique won’t work anyway so I think you’re right to take key principles from it and try to find an adapted version that works for you. There is understandably going to be some trial and error until you find what works best for him and for you but the most important thing that you want to aim for is consistency. You need to establish the same pattern of pre-bed routine (whatever this may be) and try and stick to it every night. Babies need routine and predictability to become good sleepers. From his point of view, he was used his parents patting him, sitting with him and singing to him while he fell asleep -it’s only natural that he’s going to want this to continue and kick up a fuss when he doesn’t get the usual attention before bed!
It will take time for the new routine to set but the transition will be much easier if he can predict what’s coming.

I’m looking forward to reading how you get on and I’m sure many parents who are in the same boat will find these posts extremely useful.

Good luck!