Firestick has been making a truck stake hole mount for years and it is only
$28.99. I have seen hams using them for hamsticks and most are satisfied with it. To me, it would be a compromise mount, but if you have no other options I would go for it. It is definitely better than a magnetic mount and you can use extensions to get the antenna well above the cab if you are not going to mount it on the rear. I would go for the rear to get it away from the cab.