I will be the saddle maker that says something different maybe.. re Dry spot.. If the saddle was too far ahead which it sure looks like to me, the dry spot may more likely be due to no pressure.
The whole horse was not sweated and it did not appear caused by pressure to me. Of course pics only convey limited info.
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I would look at how tight you cinched the horse. as well as looking at the horses" softness" or ability to give to the pressure / cues of the rider over all. Your horse was speaking and some of it may have been the saddle but definitely not all.
respectably.
Andy Knight