It's entirely up to you, but Black Bear is WAY overated as to difficulty. The pucker factor is huge because the consequences of a mistake are pretty gruesome. However... IF you use the pull outs on the swithcbacks and DON'T try to take any of them in a single turn, you won't have a lick of trouble in a 100. Everyone I've ever seen have trouble was trying to drop a tire off of a switchback to avoid backing up one more time. You won't need lockers if you use the pullouts. Drove it many times in my 80 and never touched the lockers... including the center. In fact, because of all the turning, I preferred to leave everything open. Normally, there is plenty of traffic up there, but since tourist season is over, I'd make certain you had at least one other truck with you. In the mountains, anything can happen with the weather and if you had a mechanical problem, that could be the least of your concerns. We had a Suburban caught in an early snowstorm up there last year and it spent the winter on the top of the Pass... I think that was Imogene, but I could be wrong.
That said, I agree with durangodds... I doubt my parents would enjoy driving Black Bear. If I was taking my parents, it would be the Alpine Loop... maybe Corkscrew up to Poughkeepsie (or however the heck you spell it). Imogene is neat from an elevation and view at the top, but can be a touch unnerving for folks who aren't used to driving steep, high altitude ledge roads. La PLata Canyon is also really pretty and probably a good scenic choice.
Lastly, as to the time frame... (and I'm not recomnmending this mind you) Van Turner and I left Durango at 3:30 in the afternoon, ran Black Bear into Telluride and Imogene out into Ouray and were sitting down to dinner at 9:30. It was fast and furious, but he had to leave the next day and wanted to do those trails.
BTW... I'm looking for a good dentist here...
JJJ