I shoot with lots of cowboy shooters who shoot .45colt,myself included.
No one uses filler with smokeless powder that I've ever talked to.
black powder,sometimes,but not smokeless..
To save money,you can shoot lighter bullets,like 165 grain or 200 grain ,but they don't do as well as the regular 250-255 grainers....too much airspace in the case for proper igniton.That has been my results anyway.
I use the same load for both revolver and carbine.No reason not to if it's for cowboy shoots.WE ain't shootin' 1" groups.
If you try to cheat too much on the powder,the primers will back out of loose fitting pockets,but there won't be enough recoil to re-seat them againgst the recoil shield,locking up the pistol.
..don't ask me how I know this.
To soothe your wife's angst,tell her loudly and proudly how one little pound of powder does almost a thousand bullets,and the brass is reusable so cost there is nil.
Heck,maybe she'll buy it.