I'd recommend leaving the rudder un-hung.  Less likely to be damaged by any number of road hazards, including tailgaters misjudging how close they are in a panic stop.  Plus which, the rudder won't be so vulnerable to your own misjudgements in close quarters where you can't see the rudder, there'll be less wear and tear on the gudgeons and pintles, and less likelihood of stripping those fittings out of the rudder or transom.

Trailerin' boats down the highway can be hard on 'em; there's a whole lot of shakin' goin' on.

.....Michael

I agree on removing the rudders.  The cycles and shock loads on the gudgeons and pintles will add up quickly.  With such a small, light rudder, there's very little disencentive to not err on the side of caution. 

I used to uninstall my 100 pound rudder on my 21' pocket cruiser.  On my Hobie, I build an astroturf covered deck with a system of bungee and pad eye tie downs that captured the rudders flat for trailering.

   I agree with Gramps. I once had two bicycles on a trailer hitch rack. I was headed to Zion Canyon for spring break. There was bumper to bumper traffic outside of Stateline, Nevada, and a guy rear-ended me. It wasn't a hard nudge but enough to make both bikes un-rideable. His insurance covered it, but my vacation was ruined.

Yeah, funny things can happen to rudders back there.

Bought a beach cat real cheap once. Then found one of the kickup rudders must have dropped in transit, because an inch had ground off the bottom.