There are many good suggestions here.
When I want to reevaluate how I get cash I usually take an hour, check out the blue rate on ambito, then see how many pesos I would get if I used Xoom, Ria, went to Colonia, etc.
In your case since you are being paid out of the US maybe a US bank account + Xoom would be a viable option.
For the last few years I've used Xoom. Never a problem except once or twice a year they want to see a lot of my documents. Otherwise I'm usually walking out in 15 minutes with my money. But they have been expensive. Now that they have a strong competitor in Ria, I see that they are giving conversion rates closer to the blue rate and have cut their fees a lot.
I considered going to Colonia but it's too expensive and takes a whole day. Maybe if I lived near the ferry it'd be a better choice for me.
A few months ago Xoom was giving me 30% less than a cueva. As a native New Yorker I am naturally paranoid about the streets but I got some dollars from the US and took a weeks worth of dollars up to a cueva. I bought pesos at very close to the blue rate (13.50 yesterday) and did the transaction in a doorway close to the street and had no problems at all. I kinda think that the cuevas know it would be bad for business if bloody tourists started staggering down their streets.
I always observe the same took common sense as any experienced tourist. I don't take more money at any time than I can afford to lose. This means that I go every 2 weeks. Always stop as soon as I'm on the street with my money and take a good look around. Get in a cab or stop again on the next block, in front of a store, and have another good look around. And dont be afraid to run or cross the street if you see trouble.
Good luck.