I wouldn't worry too much about the tires.
- The landing gear (being further back than the pin, they support a greater percentage than the pin does when hooked up) and stabilizers will support a fair bit of the weight.
- Tire ratings are based on hitting bumps at high speed. The forces involed sitting there with a little extra weight on the tires is negligible by comparison.
Get what you can off with a push broom (maybe tie a tope to the handle so you can pull it all the way across and get to the center). Otherwise, your best bet is to wait for the sun.
If you really need to move it, you could try cranking the heat up inside to 80+ and see if you can speed the melting process.