wish i was caged 
You dont need to be caged to enter...
I think he is meaning so he can run slicks, as they are only allowing caged cars to run them at this event.
Semis will be fine, remember for the actual superlap part you get an out lap and then straight into your timed "superlap" so you wont get much time to get decent heat into slicks for them to be at their optimum (especially with D14s).