Hello, I'm Chris.I will do my best to answer your question fast and accurate using the info you have provided. Thanks for visiting Just Answer.
I know what your trying to accomplish here but your not going to be able to install a temporary spare tire and wheel on this vehicle. The vehicle weight is to much, the vehicle is to top heavy, they do not make a temporary tire which can hold up to this vehicle, the brake components will not clear the small rim.
You need to purchase a cheap rim new or used (aftermarket for sure) and a new or used tire. Due to the height of the vehicle the tire needs to be the same diameter of the others on the vehicle or it will be very unsafe to drive and it will cause a ratio issue and burn up your differentials.