I don't see how with size 12's you want to stay away from wide boards yet are worried about waist size. At your weight you should be on a 152, you could easily get away with 149-150...so it seems like you have compensated for not wanting a wide board by buying an SL that is WAYYYYY to fucking long for you unless you gain 60 lbs.
You should be looking at a Revolver in the right length, and if you don't like that still, consider the Arbor Blacklist, a mid-wide, BA's (http://www.angrysnowboarder.com/
) fave stick the last 2 years running.
Otherwise just get like a 162 evo wtf...
And I think for a 2nd board its a good choice cuz you can take that SL with the dampness and setback to other situations (pow, bigger mountain).
I have a proto and I am planning to get an evo this year, I weigh 175 and ride '54s on both.