It is fine on my end whenever I use the trainer, however, the game does crash from time to time on its own, without the trainer.
Also working fine for me.
I would like to tell you that I can help, but unfortunately the trainer works A1 for me also 🙁
The minimum system requirements, the "protection" software and the early access are all potential culprits.
Did you verify the Event Viewer? This would be a good start to find out the crash cause(s).
It depends on what you hit with it sometimes, try hitting trees, rocks and other things. it should start to level.