You're right that changing models so only you see them differently is not cheating. But the use of MQ2 IS considered cheating.
And with SoE's new anti-cheat police running around, I'm sure they're looking for MQ'rs.
There is a way you can edit the globalload file to make race changes that are purely aesthetic (meaning no effect in the actual game), but I believe that method won't work either because the way EQ patches it will notice a difference in the globalload and copy over it when you log into EQ.
If you want to play specific race/class combos that aren't in the live game, you pretty much have to be on an Emu server.
Sorry, I won't explain Emu if you don't know, but as I see it, that's pretty much the only way you'll have the combo you want.