Fuel Tank IVA wording....

[CTWV50]

14. Fuel tank filling points must not be located in the passenger compartment, luggage compartment or within an engine compartment.

It doesn't say it has to be fitted on the outside of the vehicle so why does everyone fit the fuel filler outside the vehicle?

I don't intend to build in any sort of luggage compartment at the rear, there is no engine in there and I won't be fitting a seat in the back so why can't I just have the fuel filler on top of the tank?

I do intend to fit a vinyl cover on the back, does that make it a luggage compartment?

Just curious because I could save myself some money here and some hassle!