+1


i'd etch primer the steel then stonechip/shutz then paint over that


ideally you need to seem sealer the overlaps and edges and you could red oxide it then do the other, more layers the better but dont let em react and the bare steel could do with being cleaned with a panel wipe/weak thinners to get ride of residue or any anti splatter or stuff it may have gotten on it

inside chassis is a sod, if cost doesnt matter i'd cavity it a few times but you dont want to mis a mm as thats wherre it will get in next time and spread from the inside

if you could have it galv'd it would be best, or chrome!! that would rule! not rust prof with a scratch but shiney and mud would be good