I um unsure about the legalities but here is a setup we successfully have used to tow a samurai 8 hours home after i purchased it (and yes it is sitting on a trailer now)
We left the key in the ignition but left the vehicle 'off' (steering lock)
Rear driveshaft was disconnected, front hubs unlocked, and think the gearbox was in 2nd and transfer in neutral (can't remember this think that was the combination, but may have been other way round) as it means the intermediate/front driveshafts won't turn by themselves whilse not being lubricated etc etc read it on some suzuki thing somewhere...
There was nothing done to the steering or brakes. Vehicle has 2' spring lift and 31" mudzillas (have been told have to be careful with lift as it can throw the caster off and cause vehicle to wander but it was sweet)...
I used a boat trailer light bar, and put a sign on the back which said "under tow"
We had 2 issues with the steering wheel turning the wrong way, but was at lowspeeds out of a driveway when i had turned hard right for a second, then left onto a road. My passenger just jumped out turned the steering wheel and was all good. We went round roundabouts and could reverse it in a straight line no worries
I know of someone that has rolled their towed vehicle (and popped the coupling so it didn't roll the towing vehicle), from memory it hit a gravel patch on edge of road and went over...
anyway pics of a-frame: was made out of steel angle mostly, where possible joins were bolted and welded on all overlaps (lots more welding on corners underneath) all HT bolts throughout... The frame could still pivot up and down...

Now those brackets were designed to fit a stock bullbar around a stock bumper, and i was in a rush so used them (they were a cm thick though). Doing it again i would make a much simplier design that bolted into those same stock 2 holes on the chassis rails and just came straight out to eyes..
Here is another design i liked and was going to use longer term...
The eyes on the top were for an a-frame attachment point. wouldn't be too hard to make one up with the eyes on the front, and encorporating a winch mount etc... (and no tubes possibly)