What is the purpose of turning a pot roast (and can I do without it)?
I've never seen any benefit to turning a roast. If you want to minimize the crust, use a roaster with a lid or a roasting bag, but the rule is always low even temperature and slow roasting for the best meat.

A crock pot is also a good way to slowly braise a tough roast.

Coming from a beef ranch, we'd put a roast in the oven at about 100-125F at 7 in the morning on Sunday, do our chores, go to church and come home at 1 to a well done, tender roast with no turning. It gets a good crust on it which you can amp up with a good dry rub if you feel so inclined, but there's no need for turning.

Just low, slow and in a container of some kind if you don't like a crust on it.

Now, in doing just a bit of Google due diligence I ran across this article that suggests that aging is more important with an inexpensive roast than the cooking environment. We hung our beef for 14 days before packaging, so this wasn't an issue for us.

http://www.cooksillustrated.com/images/document/howto/SO96_HTbeef.pdf

If you have a big back yard and a tolerant spouse I've had very good results with the Polynesian pig-roast style of roasting. 

Dig a big hole, line it with rocks, build a fire to burn down to coals, wrap the meat in several layers of tinfoil and place on top of the coals, bury it with more rocks on top and leave for 8 hours. Delicious, fall off the bone beef from the cheapest giant Costco cuts we could buy on a boy scout budget.