Your horses back shape plays an integral part in fitting a saddle.
Low Withers, Wide Back
Low wither horses are also low profile horses, but low profile are not always low withers. Low withers is just that, they barely are noticeable.
Two problems are presented. one is the fact there isn’t a wither to help stabilize the saddle and two, their backs are so wide that you can serve a family of four off their backs.
First problem: the low withers need a saddle tree with short tree points. Yes, this seems counter productive, but keep in mind, there is less space between the wither and the shoulder blade. Solution: short tree point.
Problem two: wide flat back. The gullet and the panels plays a part as does the angle of the gullet bar, rails or bars. these are all the foundations that shape the panels that are built upon. The rails and bars will also contribute to the twist of the saddle so saddle makers have a challenge.
Solutions:
Look into the following saddle makes:
Kent & Masters Low profile, or compact
Duetts
Barnsby
DP Saddlery
Thorowgood