The answer is to take 42 (which is the answer to everything anyways!) and reverse the digits and that is how many more 160.0 tier pledges we need! Only 24 160 level pledges. So, if only 24 $1.00 level backers were to upgrade their pledges we would hit both SGs!
Just in case you were waiting, the DDP store is finally up and running! It's not the prettiest webstore, but you can use it for the next week to get in on the Kickstarter via Paypal still, if you missed pledging during the campaign.