I think I might be able to help!
Im 184cm and had this problem for 10 years up until I got this pull up bar. There’s a whole bunch of options but this seems the cheapest.
We’re lucky we live in an old house and the owner said we can drill stuff in the walls. I put the bar between a doorway I regularly pass and do 5-10 pull-ups occasionally when I walk under it. It started off with just 1 or 2 at a time but I was quickly able to do more. Within a couple weeks my back pains NEVER came back.
I had to live temporarily in a different house for a month without the bar, and my back pains immediately came back. This bar saved me from countless visits to the physiotherapist
Hmm, personally I use a straight bar (rather than the larger hooked over kinda ones) which extends out by twisting the central, part, works surprisingly well and I believe it can hold up to 100kg, are you sure you wouldn't be able to fit that into a suitcase? According to Amazon it's just over 60cm long when fully retracted.
This is the bar: https://www.amazon.co.uk/dp/B008BQ6WQQ/ref=cm_sw_r_cp_apa_jNgQAbRDZ313E