Does "E Mark" mean it's UK road legal and MOTable?
That would be just the solution for me, as I could have my second reversing light back (with the monster LED bulbs, too - I should be able to see something at last).
There are several flush fit fog lights available, a quick search on EBay
found these. As Paul said, some are more 'flush' than others, so some will protrude slightly from the bumper.
As your Bongo is already UK registered, to be MOT legal, you'll need a switch (on the dash) that illuminates when the rear fog light is on. You can pick these up pretty cheaply from most car accessory shops.
Allans Garage retired. Try PGS (Plymouth Garage Services) or Mayflower Auto Services Plymouth