I bought this foam rocket at a local Target for 2 bucks. The body is ~18" long and appears to be made from a pool noodle or at least is the same material. The hole through the middle looks too big for a BT-50 and too small for a BT-60, but I just quickly eyeballed it. It has 4 floppy fins in the rear and three in the front. Some nose weight will be required due to those forward ones. My first thought is to mount the weight a few inches down from the top and fill the front hole with some other flexible foam. That's what I did on my Fat Boi-nk and it seems to work fine. The 'ribs' in the body rotate along its axis, so it should have some natural spin. So, the fit of the central tube, the nose weight, and fin stiffening seem to be the main issues. Maybe the lugs will also be in the center hole but off-center a bit. It will be a few days until I can work on it.
You can see my three other flexible foam rockets here.