I do not shoot NRA F Class anymore, mainly because I am not physically capable of shooting from the prone without considerable discomfort and fatigue. I don't ask for accommodation, and don't know whether any is available. I simply don't wish to impose my limitations of the other shooters. That's my choice, nobody else's.
Our local club hosts something a lot like F Class, but at shorter distances, and permits a separate scoring class where impaired shooters may employ the bench. It's not F Class, but it permits a similar target size challenge while allowing for diminished physical limits. I'm not sure I like to consider myself as handicapped, or how others feel about it; but my potentials these days are clearly subject to some genuine physical limitations.
Greg