Here's Andrew's mockup of my wooden fender, which I colored a lovely burnt orange:
And here is the plan. If anything looks wrong or life-threatening, let me know:
1) Predrill five 1/8" holes on fender side.
2) Jack up the trailer. Remove wheel. Have Budweiser. Laugh at the trailer missing a wheel.
3) Position fender, mark hole positions on TD wall.
4) That was a lot of work--time for another beer.
5) Drill holes in TD wall. Make sure electric is not running through TD in case I drill through a wire and electrocute myself.
6) If I drill through a stud, this shouldn't matter and I shouldn't lose my temper.
7) Insert carriage bolts from cabin out through fender, attach washer, secure nut moderately. Rinse and repeat 4 times for other holes.

9) Figure out a way to hide those ugly bolt heads in the cabin.
Okay, is that a plan? But how's THIS one:
1) Buy a right angle bit accessory for my drill.
2) Stick the suckers on there with a bunch of deck screws, so mission accomplished and no bolt heads in the cabin to deal with.
Thanks for you opinions, and I respectfully encourage you to vote for Plan B. But please don't tell me to buy some complicated fastener that I'm never gonna be able to find in this neck of South Fllorida anyway.
Remember--you're talking to guy who needed 8 months to finally find a piece of LUAN.