Long before 3D printing was a "thing" I scratchbuild a similar fuel truck. I built it like the old-school RC wood model airplanes. The ends and couple of ribs inside are made from thicker styrene. They are connected by styrene strip stringers and the skin is very thin (IIRC 0.010" or even 0.005") styrene wrapped around the ribs. Then piece of styrene on top, and hatches made from some undersized wheels from those cheap Bachmann vehicle sets.
The cab and chassis are from a Wiking dump truck with the dumper removes.
Like the other thread says: do some real modeling.