From my limited testing with the Bunker, if you have all upgrades and have the staff focus on production, they'll produce a tad bit over $100,000 worth of stock/hour, if you sell to LS, and will run dry on supplies about every three hours. Over the course of those three hours, that makes $300,000 - $75,000 = $225,000 or about $75000/hour. It should be noted that three hours worth of stock most likely means two delivery vehicles, but, if you're a little fast, that should be doable solo. I would recommend any more than that, given the time limit.
Consider as well that, between sales, you have ~180 minutes to, for instance, sell I/E cars, which, given the cooldown time of 20 minutes for a single car, means you should be able to sell about 9 cars, for an ideal profit of $720,000 ($240,000/hour) plus any Headhunter you might do if you have the spare time for it.
If all goes to plan, that's somewhere just north of $300,000 per hour on average for something that's very much doable yourself (although it is, of course, easier with at least one companion).
That said, I'd still recommend getting I/E before even considering the bunker. It'll take a little longer to set it up, but the sheer profits are more than worth it (trust me, a few more cars and mine's made a profit of $20,000,000 after *all* expenses are covered)