Falcon Heavy is doing 6000 kph at 60 km altitude when the side boosters separate, and 11000 kph at 100 km altitude when the center core shuts down. Any energy the Stratolaunch would give to its rocket payload is negligible in comparison.

You’re allowed to land your plane on the playa. People do it all the time. You are not allowed to leave your inoperable 747 on the playa for weeks at a time in violation of the permit you were issued to bring it out there in the first place.

1.68 minutes = 100.8 seconds.