Hyper extension the spine is no joke when doing handstands. Hand horrible form for a while, and my spine suffered. Stopped doing handstands for a few weeks, then relearned proper form. OPs suggestion is great. An alternative that I found very helpful is doing the tripod balance. This is where you balance on your forearms and head for three points of stability. Holding this position is great for building the core strength you need to keep your spine in a straight line. From here, progress to balancing on head and hands. then try to press up from this position into a static handstand. After a few weeks of progression, I was able to handstand in perfect form and hold static for probably 20 seconds. I can perform one handstand pushup at a time without using a wall. If i am really stable, sometimes i can yield two handstand pushups. Try it out, i love them, and I dedicate 1 of my 3 days of exercise to strictly doing handstands, handstand pushups, planches, and transitioning from sitting, to L sit, to planche, to pressing up into a handstand. great workout for shoulders and core!