Bedsharing and side-carring our crib

We're in a queen bed and 8mo DD seems to be needing some extra space. We have a cosleeper, but it has never been comfortable for either of us to use (why oh why did they have to construct it with that silly ledge? Totally defeats the purpose!), and now DD is getting so long that it is no longer practical to use anyway. DH and I are thinking about moving her crib where the cosleeper is and taking off one of the long sides so DD has more wiggle room (she is not a restless sleeper, but she is quite active as she's trying to fall asleep).

I'm just not sure how to DO this so that it is safe for DD.

Our bed rests on a wooden frame that rises partway up the boxspring, so I know there would be 1-2" gap between the our mattress and the crib's mattress. What do I use to fill the gap so that the two beds are seamless? How do I adjust the height of the crib to match our mattress should we need to (the mattress heigh is adjustable, but in case it needs tweaking) ? How do I stabilize/attach the crib to our bed?

FYI her crib is a DaVinci Emily.

Thanks!!