I play in VR, and I suffered from pretty severe motion sickness at first in the SRV.
Drive slowly, turn slowly, and limit your time. Rough terrain is definitely worse. After awhile my sensitivity to it decreased, and it's not usually a problem for me anymore. Hopefully it will be a little easier getting used to it since you're not in VR.
Now the free camera, a few seconds of that in VR is all I can tolerate.