Simple solution on the later shells, with the bus properly supported as Jon correctly keeps driving home, leave the key on, release the brakes and do your work. If your short on air, put shop air to the rear fill valve and rock on. Leaving the key on won't hurt anything for a reasonable period of time. Now before you start throwing darts at me, this is assuming your not working on the drive axle brakes, cause if you run out of air, the spring brakes are coming on! I have quick connects on the aux air and rear fill so I can just hook my shop air direct.