My highland has a Thorowgood T4 cob in xxw - it's an older one so not adjustable. It fits him really well as the tree is quite 'flat'. Wintecs don't fit him in any shape or form!
The saddle has to be comfy for the horse, not you. You can always get off and walk, or put a seat saver on. In an ideal world the saddle is comfortable for the both of you, but if there has to be a compromise the horse shouldn't loose out. It's a huge bug bear of mine when people reccomend a saddle on the basis that it's comfortable for the rider, with no though on it being a good design of the horse
A wintec isn't going to fit a highland pony, even the wintec cob saddle. They're very wide but not flat enough. Thorowgood's are a much better design for flat wide horses but even they sometimes are not wide enough. All the highlands round here (a great many!) have Ideal Highland and Cob saddles for showing and treeless for everyday.
I have a Saddle Company saddle on the Highland, they do working hunter and dressage styles so you can accomodate chunky native shoulders. they do have to be properly adjusted by a fitter but will definitely go out to XW or even XXW
OH has a thorowgood on his barrel-shaped cob...best saddle she's ever has...plus its comfy for rider too.
ETA...our highland has a wintec wide with cair- fitted by a saddle fitter....fits him lovely, nice flat panels...(but I dont like it) he also has a Jeffries WH saddle for showing but I cant get my arse into that, its daughters.