The fuel take is bolted onto these brackets, putting the front of the taken under the frame seems a good option

Ideally the one on the left needs to vent for filling. We have put a rollover valve here so that it does this, fingers crossed. Blocked the right hand one off or another rollover valve

Front of fuel tank under brackets of frame makes it easier to fit boot cover, but some had to trim the front of the tank and sides too

This is one approach, an expensive neck & filler from Car builder with vent and ran other back to purge valve, it fills fairly easily although not full throttle on petrol pump. This picture also shows the bracket holding the boot cover, in this example the front of the boot cover is wedged against the middle bar on the rollbar with a bit of rubber and only one bracket is needed. Other solutions have used 3 brackets.

A less expensive solution and a rollover valve