I promise if I were ever the mission president I would never be living in a mansion while the elders serving under me were living in a hole. I would be out tracting regularly if I expected the elders to do it. I wouldn't be drinking black soda pop if I asked the elders to give it up. Lastly if for whatever reason I didn't, I surely would not preach that I would be the most exalted among them in the afterlife or even that I would be their equal. Those who suffered most have the most to gain in the next life and those that deny this are the true "testimony destroyers" in my opinon.
My in-laws just returned from serving as Mission Presidents in Texas. The home they lived in could hardly be termed as a mansion. It was a modest home (4 bedrooms, 2 1/2 baths). It was large enough to house new missionaries coming out into the field. Also, my mother in law worked her tail off cooking. She cooked for function after function. She just had to have a knee replacement, and I think part of what contributed to it was the amount of time the woman spent on her feet. Yes, she had some hired help, but she damned well needed it with as much crap as she had going on.
The mission presidents get a living stipend, a house to live in, a car, and are covered under Church insurance. I don't think any of this is unreasonable for the amount of work that they do.