These buses are not fragile and the precautionary information likely was written because someone was only understanding part of the story.

First, even though I have a 45 foot coach I never raise the tag. I don't care how sharp the turn, I just don't raise the tag. Here's the rest of the story.

I happen to have a coach with the Prevost installed "stabilizators" which automatically deploy hydraulic supports to keep the rear from dropping while simultaneously dumping air from the tag air bags when my steering wheel is turned to the extreme in either direction. It is all automatic. A few of us on this site have the system. Some converters ordered coaches without that system, and others disabled the system. Prevost does not support the system any more. I don't know why because it works great.

When you make a sharp turn the tag tires scuff, and the turn radius is not as sharp as possible. That actually doesn't hurt anything although it does put side loads on the tires and tag axle suspension. So despite the instructions saying not to lift the tag when moving, that is what you should do if you are in a very tight spot. What you need to be aware of is that the rear of the coach is going to drop. You need to determine before you lift the tag if the rear settles is it going to drag or drop down onto something? But lifting the tag at low (walking) speeds does no harm. I would suggest not getting into the habit however because in the uneven ground of some campgrounds lowering the rear of the coach could result in damage, especially to the rear flap, the exhaust, or even the oil pan. When you do things by force of habit you can encounter unintended results.

I view lifting the tag as a "get out of jail free" card. Use that feature if you have misjudged a turn and now you need every bit of help you can get to tighten the coach turn radius to avoid unhitching the toad so you can back up. I would never consider lifting the tag on city streets or other places where making tight turns. Any misjudging of the turn, especially if the drive axle hits or goes over a curb could result in damage because the tail of the bus has dropped.

If the coach is being lifted, it is likely it will be lifted by jacks under the steer and drive axles. I have seen Prevost lift countless coaches this way and have never known anyone at Prevost to raise the tag prior to lifting the coach.