the tank doesn't have to go in the boot,... you can get it mounted under the car,.... offcoarse that costs a bit more, but if you really need the boot then it's an option.
At the moment I am dual fuel, but I am actually thinking of getting rid of the petrol tank and replacing it with another gas tank, so my car is gas only.
I have a couple of vans I might look at converting. I like the idea of CNG duel fuel atm.Is their an advantage of LPG over CNG or vise versa?