Glad to hear that you have help on the way but if you were alone here is what I would suggest.
First remove that drop down trailer hitch which may become an anchor and turning hard left and try driving up onto the curb / wall and possibly over it or on the curb / wall with both drivers side tires until you get to firmer ground. Also I am not sure of the electronics but I think if you turn on the traction control it may apply the brakes on the side with the least amount of resistance allowing power to go to another wheel to propel you forward or backwards.
QDII and 32" AT tires. It was hard to walk on that hill it was so muddy/slippery. The Tundra drove down the top of the dam to get there, he tried to use the side of the hill like I had earlier and made it about 1/3 and had to go back out and use the high road. The hill was way steeper then it looked in the photos.
2014 Granite / Frost Beige - Limited - Lux II - Off Road II - Block Heater - CRD - 275/65/18 Michelin LTX A/T2 Tires -Rock Rails