Jim is working on a possible model and he has already kicked it off. There are some complexities and I am working on something with him as well. You may also want to check SDDCIA for hard money lenders. You can also try local banks to try to get a bridge loan of some type. I would not recommend buying at auction to many people at all unless you know what you are doing.
Good point on the HOA for downtown condos. Most likely you will not get any info about any HOA financials when you buy at trustee sale.