If you're using heavier trailers and delivering anything heavier than an old Mini or Sprite, then the Omega is only suitable, and safe, to deliver the empty trailer.
Rubbish.
I can tow far heavier than an 'old Mini' or 'Sprite' My car trailer is a twin axle, with double 16' wheel beds (rather than the heavier flat bed) which are positioned between the axles rather than above them (as on a heavier flat bed) so the centre of gravity is low. It has an unladen weight of 740kg, and my 1970s Triumphs have an unladen weight of 23cwt (1170kg), so I am slightly above the stated permissible towing weight of 1850kg when towing those.
I accept that I am probably over on the towball nose weight, but the laden trailer sits well; only slightly lower at the nose than the tail, but this is preferable for stability purposes. The outfit is very stable when laden.
The 85% suggested towing weight by the CC is only a a guide and was suggested way back when vehicles towing cabilities were a lot less - 100% is quite acceptable with more modern vehicles.
The Omega is one of the best tow cars I've had; however the Range Rover is the absolute king of towing vehicles I've had experience of, but some 4WD SUV's have laughable towing capabilities....