Ok so I have 2 amps to mount I have a TW with seat air bags and drivers is electric one would fit under passanger side but not both or under drivers the boot has a gas tank in it so I'm thinking behind the upright part if the back seat has anyone done it? got pics? or is this just crazy?

I wouldnt do it as there is no ventilation for the amps so they will get hot and you will loose your efficency with your amps

What about if I mount some mdf to my boot lid then mount them to that

so screwed to the back of the seat, in the boot area? would be arkward to do given the tank there but totally fine to do. if youve got a smallish amp, mount it in the spare wheel compartment :)

I have 2amps I'm thinking about a floor and right angle to that infront if the LPG tank