Hi cthowie and yannick90
I only check the Stronglifts forum out now and then so sorry for the slow response

Just as an update, my back is in pretty good shape. I'm still training reasonably heavy, deads, straight leg straight back deads, squats, overhead press, etc and am 90% pain free. I have re-injured my back a couple of times over the last year (no obvious reason for the cause) but have recovered within a week on each occasion. The injury has caused a significant weakness in my lower back that just flairs up now and again, it's something that I have learnt to accept.
I'm squatting at least 120kilos which is no personal best but I don't push myself as much as I used to. Deadlifts are over 130 kilos and my back is solid doing them - my grip is the main limiting factor here (no straps of course). Overhead press is an easy 60kilos so not too shabby.
I've changed my attitude a lot - I'm no longer interested in improving on a weekly basis, more like fortnightly or even monthly. I don't lift as heavy as I can or use maximum effort. For me, it's all about a steady, reliable, improvement. The truth is, I have no interest in getting significantly bigger or stronger - I want to improve on what I have and get my body strong and healthy again but slaughtering myself in the process is not part of the deal.
I train with weights 3 times for 45 minutes a week and cardio (running, rowing, skipping) 3 times for 30 minutes a week. I do dynamic stretching after every session and I do static stretching for my hams every night. Improvement in flexibility has been slow but steady and I'm more than happy with that.
I haven't tried inversion apart from inverted crunches which were a little uncomfortable.
My advice is, as always, to train within your limitations (be they based on strength or pain threshold) BUT try to reduce those limitations. If you worry about doing squats, get a professional to check out your form or video yourself and compare it with the appropriate vids you can find here. EXPECT to improve and, if you work towards that belief in a sound and reasonable fashion, you WILL improve.
Hope I helped and good luck!