Sure, why not? Let's give it a go.
Although, CR is very different than ECL. Take for example our friend the Kraken:
http://www.d20srd.org/srd/monsters/kraken.htm
While his ECL is listed as 12, he most certainly does not have 12 HD. In fact, he has 20!
CR is just a term used to designate an appropriate challenge of 4 party members of that level.
Now, according to this guy right here, Thorn as an ECL 11 charicter are equivilent to a party of 4 lvl 7 players:
http://www.d20srd.org/extras/d20encountercalculator/
(which my in fact make Thorn CR 7 if he were in the monster manual :P)
I as an ECL 5 character am equivalent to a party of 4 lvl 1.4 characters, making me roughly CR1-2 depending on various things, though I'd push for CR 2 at the least as my base race is already CR 2 as listed in Monster Manual 3. :P
Now what you said is right, 5 to 6 Soluna's at CR 2 would be a moderate difficulty fight for an ECL 11 character like Thorn. 64 of us? I'm sorry to say but 64 CR 2 monsters would simply overpower an ECL 11 as their opponent. :P
This message was last edited by the player at 02:10, Wed 11 Mar 2015.