We are lucky that our beagle is content in his bed in the camper part just behind the cab within arms reach, in our class C. We did have to train him (luxury starting from pup) to remain there and not allowed in the cab.
Do understand the anxiety. We had other anxiety issues (separation anxiety) and have found an anti-anxiety chew can be effective. This isnt a long term solution and should not be used as such. But it may be a viable short term aid in attempt to get the Goldens acclimated to being content in an area close by but outside the cab.
We used this for "calming" training. Again, dont believe this should be used other than as a training aid or for periodic anxiety problems.
https://www.amazon.com/VetriScience-...s%2C153&sr=8-7