If the batteries are 6 volt, you will need to run two of them in series for 12v. A second set can be added in parallel but you need to stay at 12v. three 12v batteries can be run in parallel.
There are a few sources for the 200w kits but you need to look at the components for quality and even if the hardware is usable. You may be better off buying the parts separately and getting items that fit your needs better.
For a 1500w inverter to run a microwave, a few things have to happen. First the fun output of the inverter has to be accessible from one outlet. Some split the output between the outlets. Second is you have to have enough battery to keep the voltage from dropping too low for the inverter to run. two 6v may not be enough, three 12v may do it.
Solar is part of a balanced system including knowing your needs, conserving where you can without sacrifice, enough battery to fill those needs for a few days when the sun doesn't play well and finally a means of recharging when the solar wont do it.
Your needs sound on the light side without using the microwave, so if you camp in a sunny local, 200w may serve you well. Living without the microwave makes it easier as you don't need a lot of battery and you can go with a smaller inverter too. Pure sine wave is recommended.
Even though we take 230w of solar with us and have never needed the generator, we still take it with us. Some day there will be a cloudy week and we will have to recharge, plus it also runs the AC when it gets hot. You can use your truck and a set of jumper cables as a last resort, it just takes a while.
On the conservation side you can save a lot of power by replacing your incandescent bulbs with LEDs. Those can be picked up at ebay for a few dollars or less each. The difference for us is we can light the trailer end to end and use less power than a few incandescent bulbs would.
Another way to save is with your TV. Some use power bricks that convert 120v to 12v to run the TV. You can replace the cord with a 12v cord and run it off of the battery instead of a inverter. Newer TVs also use much less power.
We use our panel portable meaning I can keep it aimed at the sun. On a normal sunny day it collects twice the power it would mounted.
You can't really run the trailer without battery but that doesn't mean the system wont run your trailer either. Our battery is usually in float by 9am. For the rest of the day I can turn on lights, fans, even the furnace and the battery never losses a volt. The controller will up the output to cover the load while the battery stays in float. Even with every light, fan and the furnace on, the controller only needs to put out 11a and the panel is good for 16a. So we are really only on the battery over night and we rarely use 20% even with using the furnace.
So if you really need the microwave, set it up to handle it. Otherwise it is much easier without.
2011 GulfStream Amerilite 25BH
2003 Ford Expedition with 435w tilting portable/ TS-MPPT-45
750w solar , TS-MPPT-60 on the trailer
675 Ah bank, Trip-lite 1250fc inverter
Sportsman 2200w inverter generator