Forgive my terrible phone doodle, but I think this is what's being suggested. Basically, you're groin-to-ass below, but above your chest is not pressed directly against the front partner's back. Instead, you position the lower arm so your forearm runs across their back, and wrap the upper arm over them in a half embrace.
This would work if my bed were no lt an unconscious battle field for space; if no-man’s-land exists it will be eagerly taken up, any inch given is another inch towards my partners unconscious goal of making me fall off my side of the bed. Either that or they want to be close to me. But a good thought :P