looking for temporary toilet seat riser

my wife broke her leg early in April and we are getting ready to make our first camping trip in July. We have a toilet seat riser at home since she has trouble getting up from a normal height toilet. I've been looking at options in Amazon but wondered if anyone else had found a seat riser that fit. We'd like to raise the seat height 4 to 5 inches. It's a temporary need so I'm not looking for anything permanent. Thanks!!