Back in the day we vaulted once a week up on to mats on a trampoline at Taiso Gymnastics in Saskatoon. The landing surface is excellent due to the “give” of the tramp.
In Australia this is very popular. Many of the top gyms have it as a SAFE permanent station.
Using an old, used trampoline as a base for the landing mats is much less expensive, as well.
Gymnastics Coaching.com 