There are models made by XS, Skinner, even Williams Gunsight, that utilize the holes for the rear scope mount, or in some cases dovetails for mounting. They can be harder to get adjusted, but look pretty robust as there isn’t much “hanging out” to provide leverage under impact. They are very light and compact. One I’ve used is the Williams WGRS, aluminum, but pretty sturdy, and clearly marked for adjustment.
