Tenant with a sales job, how do I verify income??

[Ben Staples]

Hi All,

I'm new to the game and have a question.  I understand the rule of verifying that the potential tenant's monthly income is 3X the monthly rent.  A potential tenant seems like a nice guy, his application looks good, and when he mentioned he was in sales, I thought nothing of it.  I get his application, and it turns out his base salery is no where near the needed amount, but he says he makes mostly commission.  My questions:

 - Should I deny him because his base salary is too low?

 - Is there any way I can verify his commission?  I'm assuming I could ask him for past pay stubs, but is there any way to guarantee his sales performance in the future?

 - Any other ideas?  

I have other options, just wanted to know as I've never come across this.

Thanks

Ben