The Summer Set by Aimee Agresti is a very light novel about an actress banished to a summer Shakespeare theater in the Berkshires as part of a community service sentence. I've only read a little of it and wasn't crazy about it, but I'll probably try again.
The other is The Understudy by Ellen Tovatt Leary (who was a stage actress herself), set in the early 1970s. Definitely a romance novel, with little conflict or excitement, but it's fun reading about theater in New York in the '70s. Worth it if you want some summer fluff (or fall fluff, because summer is like fall these days) and/or if your attention span is at an all time low like mine is. The author also wrote a book called Mother Once Removed, a memoir about growing up in Greenwich Village in the 1940s with an eccentric mother.