I trust Chemaine, and if she thinks we can improve the fit by altering my pad, I am all over it. As soon as I got home, I logged on to Riding Warehouse knowing they'd have what I need. It didn't hurt that I had a gift card still unspent as well.
I immediately found what I was looking for: the ECP Correction Half Pad with Memory Foam Inserts. this pad comes in two styles - a four pocket and a six pocket. The six pocket definitely offers more adjustability, but I felt like the 4 pocket would meet my needs. As a bonus, it comes in four colors.
Speedy hasn't seemed affected at all by the saddle's fit, but he felt really good last night. It was probably more because he'd had a few days off. He doesn't like to be worked two days in a row, and two days off suits him best. I'll hop on him again tonight. I am pretty sure he's okay with or without a few shims as long as there is a treat afterwards for him.