First post, just to be able to post links... in the next one you'll find a solution.
---------- Post added at 16:42 ---------- Previous post was at 16:42 ----------
I dont want to take any credit, cause all of this is based in others post/work.
Here you have a modified version of the sample mission posted by BearBison in his post that works in today's beta. I just fixed the problems in that one and I tested that vehicles are respawning correctly.
To find the new entity names that were problematic I used info from this other post.
I hope it helps.