A suggestion, allow Thrust with Firework Rocket.
Maybe it requires enabled on both server and client.

Juse a imagination:
Like 1 Firework Rocket = 100% thust for 1 seconds, or 10% thrust for 10 seconds. Or afterburner mode: 300% for 0.1 seconds
Maybe we can add something like fuel level, maximium volume is 1 Firework Rocket.
After the fuel runs out, it will refull with next Firework Rocket automatically. (And send a use Firework Rocket packet to server)
If there is no Firework Rocket on backpack, it goes into gliding.