Well that might indicate a problem in a rear lamp since that is a common point.
Isolation of problem is what is required at this point. "Fortunately" the problem you are experiencing is repeatible enough. To assist please print out this link of applicable lighting schematics. They aren't really needed for this first step but wanted to pass them along to you.
http://www.geocities.com/raj380/mali...buextlight.pdf
and this one for rear lamp removal. No real tools are required. The fasteners are able to be removed by hand - although pliers might be needed to get them initially loosened.
http://www.geocities.com/raj380/mali...ampremoval.pdf
when you have time my suggestion is to remove BOTH of your rear lamps on the vehicle and unplug them. Then put a new 15 Amp Park Lamp fuse in the underhood center and turn the lamps on again. See if the fuse blows. If it does not then plug in each lamp individually and see which rear lamp causes the fuse to blow.
I realize it is Sunday night so you might not have a chance to do this for a while.
Unfortunately if you do find that one of your rear lamps is causing problem it will be difficult perform a fix unless it is something really obvious. My suggestion might be just to disable to offending circuit (I will give you details) to give you at least partial functionality for the rest of the vehicle. However let's not get ahead of ourselves.
Let me know how things work out when you get a chance.