Had a Squire D10 (their smallest, 2 wheel trailer) hitched to W650 last year. Totally stable, handles fine inc braking, except v slight understeer accelerating out of roundabouts. Still have hitch and trailer, plan to fit (some time!) onto CX500, if I can mention that bike here. Bought the trailer 2nd hand but still VERY pricey. My logic (?) was wanted to try trailer experience, but thought maybe a crap one would be...crap, so try a good one first.
Long term plan is: set up trailer hitch on CX, get it right, then try with cheap trailer (eg Halfords one). If ok, SELL posh trailer! Cheap trailer can stand on its end in garage.
Things you might think about:
**takes up lots of space in garage (single wheel much better!)
**costs a FORTUNE on ferry. Perhaps only UK use.
**lower speed limit (not that cameras would notice)
** PAVs look gorgeous, but that tiny wheel is VERY tiny. If making yr own, maybe go for modern scooter wheel, ie ten inch? Friend of mine into old scooters is thinking this way, planning to turn back half of an old scooter into a trailer.
**Can't get much on a PAV. If making yr own, have seen single wheel trailer with Givi side rails added, so you can put PANNIERS on it. Seemed clever.
Whatever you do, I'm sure lots of us would be interested to see how it works out. It does seem a solution to camping with yr other half, esp long trips. And if you are in Scotland, you could borrow my trailer for testing purposes while building a hitch.
Good luck!