I’m not a physician or a nurse, but I have participated in Emergency Preparedness committees, and these are the sorts of things that are contemplated.
When a large out-break of a communicable disease takes place, you have to screen people before they get inside the hospital. You don’t want to contaminate the general staff and the broad body of patients already inside.
An overflow tent situation is considered a likely way to respond to these types of situations.
As for treating these people in large open spaces in a big tent, it may be a great idea. Now, if you can just get the inner city people to play along...
Boy, the racial tension that will come about in nanoseconds will be something to behold.
Tents in Iowa cornfields in February may not attract many sick people. I suspect we will need quickly erected field triage buildings with heaters and negative pressure rooms with HEPA filtration and disinfectant showers for those exiting in biohazard level 4 suits. Sounds like something the Army Corps of Engineers could handle. Or perhaps the large engineering firms.