>> I am looking over pfsense now. In your experience is there an issue with
>> requests coming in on one interface, returning via the default route
>> (different interface)? I see some mention of it on their docs, and not
>> having set up a multi-wan firewall before, I am not sure if it will be
>> an issue,.All traffic will return to the same ISP gateway (I think).
>>


PfSense was the answer! (Thanks Donovan). I put 5 nics in a box, and set 
three as WAN interfaces. I was able access my laptop, using  port 3389, 
from two different public IPs on the PfSense box.