For both of you it should do the job nicely without the need to drill out the original hitch. If I were to have one made up I would maybe want the plate to be about 20mm longer so all of the hitch sits on it.
Luckily the bike guy whom serviced the trailer offered to drill up the hitch to 12mm he also tried to enlarge the rim but only got to 22mm before he had to stop because he was going to hit the welding.
What he advised after that to get a serrated flange nut with a smaller flange diameter.
I ordered some (15 in fact) should be here next week.
If that fails for some reason I get the one from eBay or ask the seller to make one for me.
Thanks for the help
I will post some impressions of the 705se and trailer in action.
Cheers
Greg