They should have a Skito (or similar - there are other brands) to go with the treeless. If the fleece pad is build up like a skito for a treeless - sell the saddle with that and they can buy a different pad of different material if they want in the future. The build-up to provide spinal clearance is more important than tackiness and the tacky too pad will not provide the needed spinal clearance.
Further investigation revealed that this was an earlier model. It does have the scoop at the withers and pulls up into the neck of the treeless. The outfit has sold but I will mention the Skito. I've offered to buy the pad if she opts to get a different pad. This one will make a great bareback pad.