Plastic mudguards

State reg's have certain spec's for mud guards. Not sure of WA specifically, but would assume same as other states, requiring a turn down, so as you or anyone else doesn't walk past and slice open their leg. ( rubber will work while it is in place, but could fall off ) That could be an issue with RTA etc. I'd suggest trying a local trailer manufacturer to source them already pressed and folded, if you are not up to creating the fold down yourself.