As a coincidence - I had a discussion with an ex-work colleague who preps up motorsport vehicles to do classic trials, and he mentioned the clamp set similar to the one you describe as he alters spring ratings / spec for many trials cars. I have noted that the front struts on the tourer seem to recede after releasing the spring from tension, often inspiring much swearing and bad behaviours when attempting re-assembly. He advised me to get a set of these
https://www.ebay.co.uk/itm/CLAMP-FOR...72.m2749.l2649
Simply attach to the base of the piston rod to prevent it pulling itself inside the strut, many BMW vehicles do the same thing, and these clamps will prevent the problem, and for a small outlay and labour saving benefit, not to mention saving all the foul language outbursts that stem from bad behaviours of the piston. My set arrived very quickly and looking forward to using them !