Set Weight Minimum for One Specific Shipping Method?

website: novellyyourscandles.com

Hi all,
Is it possible to set a weight minimum for a single shipping method via code/PHP? I know I can do this via table rate shipping but I really only need it for one shipping method and would like to avoid paying for a whole plug-in for one specific need.

My situation is this: I offer customers the option of USPS Regional Rate boxes but I’m losing money on some of the orders in further regions. As a specific example, if someone from CA purchases something that’s between 1-2 lbs, they will select the Regional A box because it’s cheaper at $7.50 (or so) than it is to ship Priority Mail at $10, but my items are so small that I can’t ship one item in a Regional Rate box because it’s so large. I end up shipping it in a smaller box and having to pay the regular Priority Mail rate, causing me to lose money on the shipping.

Is there a way to adjust/enter a piece of code that won’t display the Regional Rate A box until the total order is 2lbs or over? I figured I’d give this a shot before shelling out the money for a table rate shipping plugin.

Thanks in advance!