Well that's definately one way to get rid of items in a hurry. In my opinion probably not the ideal filtering system. You have little time invested, but I can imagine the overhead involved--people you have working the sale with you, would eat up a lot of the profits you might make. Plus, if you rent 2 trucks, that's probably a few hundred right there.
In my filtering system I would run those items through an online auction first. They would make more money than a yard sale and you wouldn't have to tie up your money/time with other resources.
Donating is a great idea, but there is a cap and it's not hard to reach. After you reach it it only accounts for a certain percentage towards your income if you are doing itemized deductions--a lot of people find they do better with the standard deduction. Not that people only donate for the tax write off. There is a common misnomer that people will be able to write off a huge amount at the end of the year when that's not entirely true.
I like your idea of thinking big, even if in these times (with storage units going for inflated prices)it might be extremely hard to do. I hate to say it, but if you want to be successful in this business you have to diversify. You can longer count on one source for your product or one avenue to sell product.