Sounds like a dream to me, especially the part about having room for the panels and batteries. I see great deals on both and don't have the room to take advantage of them.
I look forward to watch you set your system up. I would suggest that if you do start with two big panels that you get a controller big enough to handle the upgrade should you ever decide too.
As for how much of panel or battery to get. You need to figure out your daily uses on average. you can use a flow chart or like I did, went camping for a year and paid attention to the daily drain on the battery. Once you know this you need enough battery to hold you for a spell when the sun doesn't play well, say 3 days. When the sun does come back you need enough panel to bring those batteries back up in a reasonable amount of time or you can get into a situation where the solar can not get caught up and you need to run the coach or a generator.