How do I put two single beds together as a double bed?

My boyfriend and I have recently moved in together in a dorm room and we're looking for ways to put the two single beds together as one. They both have a metal frame at the top and bottom parts but nothing is higher than the mattress level on the sides. The question is - how are we going sleep/ cuddle comfortably at night without ending up in the gap and pushing the beds apart during the night with our body weight? We thought about getting an additional double-bed mattress on top of the beds, but would that be sufficient? Do we need to tie/ tape the bed's feet together or stuff the gap between the beds/ mattresses with something soft? What would you suggest? Thanks!