If it's rated at 2Ohms, that's what you should load it with for maximum output power without blowing up. However, you say it is "rated for 1000W at 2 Ohms" with "2600W peak". The peak rating is also at 2 Ohms, so the 1000W is RMS? 1000W at 2 Ohms is about 22A of current. Assuming you have perfectly efficient amplifiers (and DC converters), this will draw about 80A of battery current at 12V continuously.
Be sure to use thick cable: 2 Ohms are easily "diluted" with cables adding significant resistance, and if you lose 200W in the cables, their insulation might melt, getting you into problems.
At any rate, while a car is a comparatively small space, 1000W RMS of subwoofing seems like a rather inefficient way of cleaning the windows from inside. I definitely hope that you have no passengers inside while doing that procedure.