I don't know whether you can send dollars to yourself with WU because I've never tried it. But if you have a friend or family member who can send you the dollars, you can easily pick them up in Uruguay. I used to do this all the time during the last cepo. I would get someone to send me dollars to a Western Union in Uruguay, then I would hop over, pick them up and return in one day. The most I collected was about $3000 USD, but I'm sure you can pick up more.
One thing to note is that (in Colonia at least), the WU office would ask me to call a couple of days ahead to book the amount I would be picking up so they could make sure they had it available.