I think even if you didn't use the bolts, the sleeves at least would be helpful I think in reinforcing at least a small part of the frame. But if you've got the holes drilled, throw the bolts in there.
I'm installing some TNT stiffeners in 3 weeks, and I plan on getting the RK kitlater. Since it will be on top of the stiffeners, I can safely weld all the way around it, But i'm still planning on putting the bolts in.