Hi DAVIDOFF/David,
The comments about paper have been covered & you know it is ok, but with constraints/tradeoffs…
Hmmm… just a thought, which you have already eluded to in your post, but maybe want to take a second look at - a collapsible background option, perhaps something like this quality item (given your apparent preference for white & grey backgrounds)
Lastolite 6ft x 7ft Collapsible Background (White/Mid Grey) Mfr# LL LB67GW:
http://www.bhphotovideo.com …L_LB67GW_Collapsible.html
http://www.lastolite.com/collapsible-backgrounds.php
(as you know UK based)
This would enable your ¾ shots(head to knees) criteria, with enough space for say 1-5 adults, occasional props/chairs/benches etc. which you sometimes use, have versatility with color gels (like wisely experienced SKIPD POTN user usefully indicated) and also transportable in a normal car, since as you know it collapses to 1/3 its size.
[Yes I too wish I had a truck sometimes and I recognize European cars often tend to be smaller than North American cars; I have several collapsible (& curtain) backgrounds including this Lastolite 6ft x 7ft Collapsible Background (Black/Mid Grey) http://www.bhphotovideo.com …L_LB67GB_Collapsible.html
which even though I’m only 5ft 2in (157cms) find it very versatile & portable, can support itself without a stand if required, or leaned against something like a wall and without the wrinkle/ironing hassle of my other muslin backgrounds and it fits in my small sports car’s trunk (BMW 135i coupe)].
Its just one option, but a viable one - good luck in finding a solution that works for YOU…
Mary