Seems to me the biggest problem with lpg is where to put the tank.
Im a big fan of lpg having owned 4 vehicles in the past with it. Every car I had with gas was 40% cheaper to run than on petrol. Now have a stag and even though i love it, the fuel bills are cruel.
Last car was a vl on gas. ( Cheaper to run than the wife's echo) Tank was a torroidal (doughnut) in the spare wheel space. Big improvement on the great blob inside the cargo space option. Problem was it still sat about 60mm proud of the floor and used to shit me as well. Also stags use a space saver spare so nowhere near the depth in the spare wheel well as a full spare space.
What if the petrol tank were replaced with a manifold tank, then a small petrol tank be manufactured and jammed in somewhere so it could run duel fuel?
That would leave the cargo bay uninterupted.
Also something no-one who sugests dedicated lpg has mentioned........its a real piss off having to get towed to a fuel station if u run out of gas. You cant go for a jerry can of lpg........ Been there done that. Also found myself in the situation of not able to get it in a particular area or the delivery didnt come etc. Then you're walkin.