the big tank up front is for my long trips away,
prior to this i used the main tank for veg and a 10ltr start up tank in the space next to the exhaust manifold,with a heat sheild, that was fine for years.
Now i use the main tank for start ups, the big tank up front for veg, but ive still got the little tank under the bonnet[not normaly used] so that if i go for a long trip i have the ability to use both big tanks for veg.[250 ltrs] and the little tank for start up shut down
just a thought , if you place the tank inside can you still put the seat down ,if you need to transport various cargo