I’d say so… Not for the reversing but for going the wrong way up a one way road. I guess the answer to ‘I have no choice’ would be to “use a suitable vehicle”.
Tell him you only want to go one way.
I’d never use my money to buy a trailer with mud guards. Just get that flap bit down the side with an easy rip flap at the back a la Schmitz & Cherau & you’re good to go. Suppose you have to have them on a Skelly.
I used to have mudguard problems with the wheel locks that roll up the front of the rh rear wheel as you back over it. Just trimmed a couple of inches of the front side of that mudguard on all the trailers and no more problems. Did them one by one as they came on for inspection.
When they were damaged we did always get paid for them though. If the wheel locks weren’t there then the trailers wouldn’t be damaged.