Chels08, Erin and Jasper
Could you post some pictures of the wither area?
Also what type of Western Saddle are you using that is too wide?, Chels08 it sounds like you may be using a Full QH Bar Saddle that is just simply too wide, not only is the Gullet to wide, but the angle of the bar is wrong.
Padding up sometimes works depending on the Horse and the Saddle, but is not always an appropriate fix.
Some pics of the Horse and some pics of with the Saddle on the Horse without a pad will help us judge the fit and potential fix.
A new Saddle is not always an easy fix to do financially, but basically fitting TB's is not difficult, but many times cannot be done with the Average off-the shelf Saddle, but with some pics and a measurement or two, the proper saddle is not always a expensive as you might think.
Sometimes an off the shelf Saddle will work, it just may be a little harder to find.
May all your Trails be happy and safe ones