I'll delete this picture in a week or two:
IMHO, too much pad for the saddle. It lifts the saddle up enough that there isn't much left to hang on to Fly's back in a turn. With decent saddle fit, 1" of padding is plenty - near the upper limit.
"She wants me to get a pad with 3 shim pockets, remove the back and keep the middle one in (to fill that bridge under the gullet where there is not enough contact against Fly's body). By closing that bridge, it will distribute the weight of the rider more evenly and more weight felt towards her hind end which is what you want. It will also lift the very front of the saddle enough to take some pressure off her withers.
Makes no sense to me. If the saddle doesn't touch the withers with you in it, it is clear. Can you take a picture similar to this:
And maybe try riding her with just
a 1" felt pad? NO shims, no doo-hickies, just a felt pad between the saddle and Fly?
"Why are roping saddles so heavy?
Because if a steer hits the end of the rope that is on your horn, having the saddle come apart will ruin your day? The tree of a roping saddle, and the horn, need to be built up strong enough to handle loads a non-roping saddle will not encounter. And that adds weight.
"They will have extra rubbing when they turn their heads, and more insulation where they can just develop more sweat
Doesn't work that way. Not even close.
"If I gave my horse this many cookies, he would be pawing, too.
Mine would be so fat we'd have to put him on roller skates to move him.