Yep got that now, paint it is, what colour? Orange to tie in with the special vehicle plate ?
Use Bonda Zink primer for long term protection from rust. It's designed for marine environments and so last years on cars.
https://m.ebay.co.uk/itm/BONDA-RUST-PRIMER-ZINC-ANTI-RUST-PRIMER-2-5-LITRE-/321117430271