I know what to do with a gas powered MH when we are living in it parked for a few months. That includes topping off the gas tank and adding Stabil. Taking it out for a drive once a month and exercising the generator.
What should be done with a diesel powered MH?
We do the same as you do with your gas powered. We make several stops in reverse & turn off retarder electric toggle switch to make sure brakes get exercised. Run gen under load.
What is the reason for this?
Slack adjusting?
We back up just to get all the brake parts moving through their full range of motion. I could see brakes getting little use when retarder does all the hard work, so putting them thought their paces forward without retard and backward to un-glaze linings, etc. And after sitting for a month or so, I would not want brake parts to seize up.
Does applying the brakes while backing up adjust the slack on disc brakes as it does on most drum brakes?
That was why I asked "Why in reverse...". It is my understanding that the Meritor auto slack adjusters "do their thing" under normal operating conditions, i.e. braking while going in a forward direction.
But Barry has answered my question. (I think) he is not concerned particularly with adjusting the brakes - he is just trying to exercise them in all possible modes to preclude any problems down the road. Applying his brakes in forward and reverse is a excellent way to cover all the bases. Sounds like a good idea to me!
Consider a biocide rather than just stabilizer (Biobor JF, StarTron Starbrite are a couple that come to mind) with the diesel if not in an arid environment.
Check tire pressures. Check for puddles around & under the coach. Check that insurance and license plate(s) are up to date.
Check balances on credit cards and bank account. (just in case)
Also, wouldn't hurt to walk around and look for any damages due to weather and/or vandalism.