Hgt wings are wider because it has a wider front track. Chassis is exactly the same.
The Hgt sideskirts will fit lesser models Id say, there'l probably be a bit of a gap where the sideskirt meets the wing, but you could fill this with a good rubbery silicone.
Ive fitted Alfa Romeo 146 sideskirts to my Jtd, and neatly filled any gap with silicone, lucily my Bravo is white so wasnt hard to find a matching silicone colour.
Anything is possible ... dont be put off by stuff you've heard that they wont fit.