Wheel clamps come in many different designs. In my opinion the better ones not only lock the wheel - or rather stop it being turned - but cover the wheel nut(s) to stop any potential thief removing the wheel. You can also add a little more security by fitting special wheel locking nuts to each wheel. Any way the choice is yours and anything that makes the thief's job harder is bound to be a good thing
I bought the SAS one when I purchased my TT. It doesn't/didn't fit properly. I could just pull twist it off the wheel. I phoned SAS who said I needed an additional part that fits over the wheel nut before the clamp...not mentioned in any literature!! I have a Cabanon TT...very uncommon obviously !! I reluctantly bought the part but I am still not confident that it will stop anyone...but its big and red so looks the part.
I would not buy either unless insurance approved and fitted correctly. the easier it is to put on the faster it is to remove for the tea leaf. Most insurance companies insist on Alko type wheel locks but some do recommend or accept other brands along with a tow hitch lock. Why don't you ring and ask your insurance company might find your not covered if you fit either of your choice. I have an Alko wheel lock which is one of the hardest dam things to fit. I move van back and forth to get near as dam it then fit wheel brace on one of wheel nuts and turn wheel in required direction while pushing cast block in between spokes, soon as it aligns up it slides on to tube fitted to chassis easily, the rest is simple
I suppose a sensible question is to ask what trailer tent you have and what sort of wheels it has? if its Cabanon and steel wheels you might still get the problem with the milenco that I had with the SAS. Fingers crossed you don;t, let us know.