Biggest tank you can fit in a combo van

[petehughesy]

I've got a 53 reg combo, currently I have a 400ltr upright tank down the middle and I use a backpack trolley, I want to put a hose and reel system in but there is just no room, so I'm thinking of a flat tank now, but I'm not sure what's the biggest size flat tank I can have, I've measure my mates 250ltr tank which would fit but ideally I need bigger

 

[tench0771]

a 350l flat should fit long ways

 

[tench0771]

a 350l flat should fit long ways

i can mesher mine if u like?