Mike, let me see if I can sum up your questions;
1-you have damages that exceed the security deposit, can I collect the difference?
2-your tenants failed to follow lease stipulations regarding showings and access; can I make a charge against the security deposit for breach?
3-I failed to include monetary damages for the failure to allow access to show, instead calling for a 'forfeiture of lease", can I now backtrack and use the security deposit for that?
In my state the answer is simple; 1 is a yes, 2 is a yes, if damages are stipulated and agreed to, and 3 is a NO! You already stipulated that the lease is "forfeited" (whatever that means) and now can't arbitrarily collect on monetary damages. You may have been unclear on that point in your post, but I have to question the language. Typically, you need to show the property when the tenant is moving out-so why would you put a penalty in that is moot? They are already leaving, so 'forfeiting " the lease is useless as an enforcement.
However, you can ask for anything in your suit for judgement, if the defendants don't answer, you have a default judgement; the validity of the claims is no longer able to be challenged. If they do answer, let the judge decide.