The Willow Hole Cowboys in North Zulch offer a 1911 category in every cowboy match, integrated into any posse. The 1911 shooters use 5-round mags, shoot the scenario like cowboy shooters except that somewhere in each scenario is an instruction to shoot ten pistol rounds at the rifle targets. Ten rifle, 20 pistol, and four shotgun. Would that work for you, short of a full blown WB match?
The idea from Dusty Boddams has merit. And a WB posse needs only five and good organization to function - the TO, three spotters (one keeping score) and a shooter.
Persevere!