Apple Magic Trackpad - Avoid accidental cursor movement
I believe a third party app called Better Touch Tool could help you out. It costs around $8, but it does have a 45 day trial.

I'd say for the most part this app is for customizing gestures or just setting hotkeys and stuff like that, but it has pretty robust settings for alleviating these types of trackpad issues.

The trackpad settings can be found from the main window on the top right. Though you may have to enable advanced settings on the top left of the window before you can see the trackpad settings.

Screenshots of every single page of these trackpad settings:

I highlighted settings that may help you the most...