Well, here's why I think it should be easyish.
Detaching is a problem that a few people have solved, in a few ways. So, build a glider - body tube, wings with a little dihedral, tail section, nose cone - with a motor mount and trimmed with spent motor installed. Simple. No shifting the CG or the CP, no moving parts at all except whatever is involved in the release from the main rocket.
But the main rocket is a lot taller than the booster, so when the booster is attached to it, all those surfaces that make the glider work are just lots of oddly placed fins. The rocket after separation is just a 4FNC. Before separation it has a bunch of extra weight aft, and a bunch of extra fin area to help compensate for it.
I won't say it's altogether easy, because I'm not that naive. But I think it sounds simpler than most glide recovery designs, because you don't have to adjust the CG for glide.