I like your thinking on the Base Salary. Every company I ever got a base from had a 90 day "Get the Hell Out of my Business and don't ever come back" clause. I also, had a minimum monthly/quarterly quota to maintain that equaled in commissions to the base salary. So, the company wasn't paying me money when I didn't bring in enough to cover my base. If I fell below quota the checks were reduced accordingly. This way the company is only out 2 weeks risk at any given point in time.
However, if your only paying 9-13% commissions. I wouldn't accept the offer anyway. That is just way to low for a serious top producer.
I usually get 25% of the profit per job with a base salary & house lead generation house owns the customers & leads generated had to register my contacts, or 40% without base (25% commission on all house leads) clients are fair game upon termination still had to register contacts. On both I also get a minimum $10,000 a year Marketing Material/Trade Show Expense account, along with cell phone allowance.