Splunk can handle may routers. I have just set it up for more simple to use in my project using Splunk for MikroTik routers.
One nice thing with it, is that it does not use SNMP (SNMP is good at many things, but does not like dynamic IP).
You just add a script to each router that do send you all the info you need periodically.
I do assume you could make a master config and install it using netinstall before shipping the routers.
It worth test it out, hva a look at link in my signature, or here:
http://forum.mikrotik.com/t/tool-using-splunk-to-analyse-mikrotik-logs-3-3-graphing-everything/121810/1