The proper thing to do is read the land...Safety is one of the big thing when electing to take the shotgun from the vehicle instead of the rifle. Carry both...Make sure your car or vehicle is locked so someone does not break in and steal it off you....
Calling in the early season......The shotgun might be better since the corn is up and the soybean is up yet. Your visual area is small...Once the corn gets cut you can start to use the rifle.
Also remember this too....Most times you have to intercept the predator when using the shotgun...They have to come past you or near your stand... Rifle.....You just have to get them to come in and show themselves at about 100 yards... Even the JS Preymaster that is not remote controlled is an excellent riflemens caller. Get the fox to just move into rifle range....Mouth calling is outstanding for the riflemen too......Shotgunner you almost have to know how a predator acts....Kind of figure where he or she will come to the call.
Remember this most times......Predators will enter into the wind to scent the prey distress sound...Also they will get in direct line with the loudest part of the speaker or mouth caller...If you know this...now set up at that proper spot to intercept that red, gray, coyote, coon...
Your a mammal......The predators are mammals...Now just start to think like them......