Started boarding out the inside, it has to be done before I weld the door shut.
Surprised @ that given their practically even if only using tiny hidden buttons to open them for the cleaner look. Relocated number plate looks much better without messy lamps to clutter the tailgate. Some bumperettes with plate lamps in the ends would finish things off nicely.
With a full-on panelling like the butcher shop van, shut welding the doors would be "demandatory".
But when You keep the recessing and c-pillars, it's not really necessary. I would leave them functional as doors, to be opened from inside.
I would maybe even reduce the inner sheetmetal, put in some sort of shelving and use them as space for small stuff (don't know Your transport needs), if only for first aid kit and warning triangle for quick access.