The diagnosis of SCLS is made partly by exclusion, namely, by eliminating the possibility of other more common diseases, and is based on measurable, clinical symptoms such as hypotension, hemoconcentration, hypoalbuminemia, and the presence of a protein called Monoclonal Gammopathy of Unknown Significance (MGUS). Every time you went to the ER and they drew blood and monitored your blood pressure was an opportunity to have the diagnosis of SCLS confirmed or rejected. The periodic drop in blood pressure you cite is not sufficient evidence. You and your existing doctor should have the ability to get you out of limbo, by gathering your results, examining them for tale-tale evidence, and sending them to Dr. Druey at NIH for evaluation.
With regard to your question, it is highly unlikely that you will ever "find a doctor who will be there if I have another major episode." Your best bet is to print out the Wikepedia write-up on SCLS and hand it over to the triage nurse who will screen you upon your next arrival at the ER. Have the ER measure you for hypotension, hemoconcentration, hypoalbuminemia, and the presence of a Monoclonal Gammopathy of Unknown Significance (MGUS). If you test positive, then they should continue to follow the instructions provided there, in order to treat you appropriately. If you do not, then return to Mayo for a thorough evaluation.