If you plan on eventually building, why not plan ahead a bit?
Figure out roughly where you will supply power to your house, get the utility company to come out and install poles and power lines. Then get an electrician to come out and provide you with a temporary panel and outlets, 15 amp for regular stuff and a 30 or 50 amp for your trailer which will run your Air Conditioner. Hiring the electrician would make it all legal and according to local codes.
This process may be way more than solar panel and batteries, or purchasing a generator BUT you will eventually need to get power to the site even for the building process, and doing it this way will allow the bank account to recover a bit from what I would think is a pretty costly item (power). Also running a generator for brief periods of time to recharge batteries, run AC, use the micro-wave is fine, but to listen to a generator humming away for 8 hours is simply nerve wracking, try sitting in a campground listening to your neighbours generator run all day long.
2012 Sunset Trail by Crossroads
2016 F150 Lariat