well...........................
the full-cages can be used as half cages actually :) just don't bolt-on the front hoop.
oh btw, half cages are useful for roll-overs only, nothing more.
might as well put it a full-cage, at least got better protection.
to be safe:
SuperLon pad it (thick 19mm) all the vital areas (head, mostly)
4 point harness (properly mounted, thank you)
full bucket seats
brand new proper spec bolts for the cage. Tightened properly.
then now you must come/cook up a plausible explanation why you need a cage in your car to JPJ
*all my advice are for your viewing pleasures only. Whether you choose to follow it or not, i'm not liable for anything, especially problems that my advice may cause. You should be mature enough to make your own judgements :D