The idea of "opportunity costs" is based on the fact that critical resources are always in short supply and if I dedicate a resource for task R then I cannot simultaneously use that resource for task U.
Watching Antifa's urban tactics, you cannot help but notice similarities with cowboys driving cattle or WWI Russian serfs attacking German trenches. Lots of cows and serfs and very few cowboys or officers.
Obviously, the great mass of BLM or RvW or outrage du jour protesters have zero training. The most the Antifa officers can hope to accomplish is to distribute signs and things to throw, point the direction of attack and to reward with promises of looting and burning. If tactics as sophisticated as flanking maneuvers or ambush happen it is by pure happenstance.
In spite of what some observers, including one high-profile Michigan based observer* claim, it seems impossible that Antifa could field enough "officers" and enough modestly-competent foot-soldiers to field 50 effective "soldiers" in one small town 30 miles outside of an urban area.
They could probably field twice that many "cannon-fodder" bodies (hence the comparison to the Russian serfs in WWI) in one small town. Their goal would be to provoke an over-reaction and to create video footage that would be the stimulus for government reaction.
The risks to Antifa are many. Locals taking out the transportation would have the soldiers walking. Few things are more humiliating to young adults than to have to WALK! Another major risk would be if the locals could noodle out the top echelons of Antifa leadership and neutralize them and nobody else.
Antifa has no problems recruiting ushers and traffic-control type leadership. They also have no problems finding people to fly drones. What they lack is a robust system for replacing the few high officers who can integrate the information and run the show with an ear-bud and hands-free mic. The potential replacements with the competence are not trusted. The zealots who are trusted lack expertise.
Attacking rural towns in any numbers would present Antifa with grave opportunity costs. They would not have the resources to close freeways and public thoroughfares in urban areas which is their current high-leverage tactic.
Even commando-strike tactics aimed at rural towns would deplete high-end Antifa leadership in short order, especially if churches, pregnancy counseling centers and other potential targets used geo-fences to identify cell-phones in the immediate vicinity.
*To the best of my knowledge no independent verification of super-competent, Antifa leadership has been offered by other observers. The "expert" runs a martial arts dojo and probably finds the free publicity profitable.