I decided to go with rivnuts for the reversing & fog lamps, much easier to install/remove/adjust them than with the standard nuts & bolts that come with the lamps.
Extra care opening up the mounting holes to 9mm, the fuel tank is sitting about 20mm behind the rear panel. Then I used a scrap bolt and pliers to bend the rivnut to sit horizontal, rather than at the panel angle:
The lamps were already modified but I also had to sand down the posts that the bolts fit through so the casings would sit flat against the rear panel. The fog lamp must be aimed horizontally and not point upwards to pass IVA.
The only gotcha was the loom label on the offside cable, I should have removed it before feeding the cable through the hole/grommet, it needs to come off to feed enough cable through & was difficult with the rear panel in place.