A few recommended a gymnastic studio.  I used to do gymnastics a million years ago.  A crash mat works for limited  height tumbling failures. Also the coach  could possibly help.

If you can get 2 or 3 matresses ( at least queen size) .. that should be more than enough ..

Just have the model practice a few times from the ground ... so she has an idea of how to throw herself ..

As a kid i used to jump of  the roof of a building (top of a first story building which was slightly higher than residencial) near a friends house ..  onto some matresses all the time ..