Don't get rash and impulse buy an inverter (or any other "appliance"). SternWake is our resident battery guru. Some of his posts are very detailed (he points to perfection and then lets you decide how close you want to get to that) and there are others that know way more than I do. You are going to have to figure out ampere hours. :huh: This means how much does something draw and how long is it going to be on. Only then will you know how much battery and recharge capability you need.
There are two types of inverters to change 12v DC to 110v AC. Modified sine wave (MSW) and pure sine wave (PSW). Modified sine wave inverters are a lot cheaper but there are a lot of AC appliances that will not work or burn out if you use them. There are losses that are lost to heat in the conversion process too. Getting 80 to 85% efficient conversion would be good.
Anything you can run natively off 12v is best. I use a 12v adapter for my laptop and my desktop computers. The TV I use as a monitor is a 12v TV. A 12v crock pot (to use while driving and placed in the sink for spills), a 12v RoadPro lunch box oven. Our CPAP machines run off 12v too. I am sure I am missing some things, but I am trying to point out that a lot of things can be run off of 12v if research is done. Every light we have has been converted to LED except for a fluorescent fixture we never use. I upgraded our converter/charger that came with the Roadtrek as it is a known battery killer with a Progressive Dynamics unit that was a direct replacement. It converts 110v AC to 12v DC and is a battery charger too. For this to work, the generator must be running or be plugged into shore power.
To use the air condition method you mentioned for your pet, I think you will be buying bagged ice and a computer fan to move the air. The linked to ice maker doesn't show how much power it draws....
I think you are going to have to make a list in the order of priority of what you need to work on:
Commode - They make liners to put in the commode (normally for Winter camping but can be used any time of year). I think they are called wag bags. A place to store the used liners until they can be disposed of. Other's here will know a lot more about this.
Drinking water - a 5 or 7 gallon water container and some 1 gallon water containers. These will be useful after the water system is working to help extend your stay.
Cooking?
cooling?
cold food storage?
etc.
We have had our Roadtrek a year and a half now. I have just about got it to where it works for us. Thank God most of the built in appliance worked when I bought it. I did have to R&R the generator to get it working though and recently replaced the HW heater. The fridge will probably be next. The fridge holds a surprisingly large amount of food with a good sized freezer and is a 3 way, 12v for when driving, propane when camped, and 110v for when on shore power. I have placed remote temperature sensors in the fridge and the freezer to monitor temps (no soupy ice cream). Remote temperature probe on the HW heater so we know when to turn it off so we don't waster water trying to mix hot and cold. New front end parts including ball joints to brake rotors. All fluids have been replaced, brake, trans, radiator, etc. and recently a new exhaust system and tune-up. Any older RV/van is going to take work and money to get it to where it works for you. I started early as I knew there were going to be things to work through. My last day of work is Jan. 4th and is when our adventure begins.....
Make that list and start working the list.