Sleeping single in a double bed

My partner recently came back from his trip, and I am very happy. Thats a good sign after 3 years. I still get excited to see him. I will say though that while he was gone he grew an affinity for sleeping in the middle of the bed. This was a habit I had broke him of a couple of years ago when I awoke clinging to the edge of the mattress and he was spread out like a bed spread. Now I must train him all over again. Its up to him weather he wants to make it easy or hard. I am not opposed to pushing him onto the floor. Pair this with our dog Misty sleeping at the end of the bed, I believe I may have to take drastic measures. I know he can't help it, after all he is asleep, but I am growing tired of waking up in a fetal position holding on for dear life. I think if I am able to keep Misty off the bed the first battle will be won. Next I believe I will have to take the middle part of the bed when I first lay down. If I hold steady and do not budge, I will succeed in keeping him on his side, but there is a trick. We cuddle before we seperate to our sides, that is how he manipulates the bed, he is very savy.So my plan is to cuddle with him while he is on his side before he reaches over to me, that way I have the upper hand when we seperate. I will let you know how it works.