If needing a tire in the middle of BFE (without cell service) I would remove the unmounted spare from my roof and install it... yes I'm still capable of doing that. If no spare then I'd remove one of the tag axle tires and put it where needed and increase the drive axle tires on that side to max pressure. I would take the air line off the airbag on that side and plug it off so it does not push the axle down too far.. Note to self... get a plug that will fit that hose from my shop although you could bend it 180 to seal it off.
On the Monaco's that lift the tag we have a pair of air chambers and chains that raise the tag axle. If the side without a tire still needs to be held up then changing the length of the chain would be the easiest way to hold it up BUT the air line would need to be plugged on that side.
If you remove both tag tires there is no need to chain it up as the shocks will stop it before it hits the ground BUT you need to make sure the arch that goes over/under the drive shaft is not going to hit it. If it is going to hit, it would be easy to reroute the tag's airbag lines to the air chambers that raise the tag IF you had a pair of male couplings... add two couplings to the list.