Front facing, or side facing?
Side facing are a bit skinny for full size people over any great distance, but you can get four people on them in the back of a 90, 8, in the back of a 110 3-door, or 6 in the back of a 110 CSW, so maximum people capacity, and they take up least space so leave most room for load when not full of people.
Only thing about them I found was that the cusions had a habbit of bouncing off the seat frame if no-one was saat on them.... solved by velcro...... the frames rattled, when no-one sat on them.... solved with a bit of camping mat foam glued on the seat box...... the frames wouldn't stay 'up' when folded..... solved with a bit more velcro on a tape..... and when you folded them up, you had to find some-where to store the seat bottom cusions........ (They will fold with the seat bottom, but doesn't make much more room)
As for straps, personally I fitted four point rally harnesses, bottom straps fastened to the seat-box with big spreaders to the floor ribs, and the shoulder straps to studs through the tub-rail.
Worked well, and kept the kids well held in, offering full support in all directions.
Didn't like lap straps, they didn't do much.
Foreward folding seats, are bulky and a bit of a pain.
Can be mounted to face backwards, which makes them a bit more practical, but basically, you can only get two in the width of the body, and when folded out, IF facing forewards, theres no room for a full sized persoin to scramble over and into one.
Facing backwards access is easier, but, pretty much, two is your limit, whatever vechile they are fitted to, as other wise, no one can get in one, and or get in it!
Straps on them tend to be to the frame, and a lap-strap is about as much as you can have.
Onto the legalities...... gets confusing, but on pre 1985 vehicles you dont NEED any rear seat-belts.
On ANY side facing seat-belt, you dont NEED a seat-belt.
BUT, if fitted, they must conform to regs and be securely mounted, and any-one in the seat must use them.
There's a whole host of curiocities in the regs about putting kids in cars, and where they can or cant sit, depending on where seat belts are.......
But personally I've found common sense prevails with the 'enforcers' as the interpretations of the rules are as bewildering to them as to any-one.
You DO need to inform your insurance company though. Five seats they will normall be happy with. Seven seats in a 90, they may frown at, but you point out thats the 'standard' seating capacity of a 90 CSW, likewise for 10/11/12 id a LWB.
BUT anything over 7, is likely to raise an eybrow and may incurr an insurance loading; and anything over 9, I think you need to check your licence carefully, as if you past your test after about 1997, they changed teh groupings and you need a mini-bus licence to drive it!
