Actually, you have some options, but you'd need to restructure your portfolio. The possible solutions involve some sophisticated, commercial transactions that many here would find to be largely irrelevant. Please feel free to contact me: I'd be glad to look into and discuss this with you further.
There is no portfolio lender that will do a loan for 3.5% down unless they are absolutely insane.
I know of no portfolio lender that would touch this unless you have significant down payment in the range of 40% and significant reserves to the tune of 6 months PITI for each property.
Sorry to be blunt but no sense sugar coating it.