Unfortunately, the Watling one is only suitable for even older models that the 2011 VW that I drive.
What "mark" is your Golf GW? Is 2011 a 6? You're probably aware, a mk6 is more or less a mk5 (from about 2005?). I believe rear tow bars are compatible? I know a mk 3/4 rear bar won't fit a 5...see below.
We currently have a 2012 1.4 TFSi petrol cabriolet GT, "sort of" a Mk 6 (wife's, not for towing) and the front underside seems very similar to my long-term 2007 mk5 gti (excepting bumpers, "aero" etc). Although the cabrio does have a very large, heavy gauge aluminium undertray, that is plastic on the gti. The rear chassis seems to be significantly different, probably due to cabrio mods?
Could you sacrifice style/aero?
Or, see post above re bespoke front bars?
Or, buy an old Golf as a tug
that said, even bangers seem to be commanding silly money atm. I have need of a "shed" for my current projects, and there's little hereabouts under £2k with a newish mot... personally, I'm still coming to terms with the £1k banger!
Older Range Rovers seem abundant, unloved, and perhaps "good value". You can have a 2007 RRover for diesel Golf money, almost like-for-like!
.....but I'm not that brave/stupid and have no need of an additional hobby!
Ps, I have both roof racks and tow bars for Golf mks 1, 3 and 5 here somewhere...none of which, of course, fits our current cabrio!