You may also want to consider a small generator, say about 2000 watts, maybe 1800. I have a Honda which you can buy new for about $900, but there are other brands that are a bit less expensive. A generator will allow you to recharge your battery or run a microwave while boondocking. I don't know enough about solar, but I can see the benefits. Just not sure how much power you can get from them.
A friend is looking for a good used pickup camper, specifically a Lance or Artic Fox. He's done research and this is what he wants for he and his wife in retirement. Already has his 4wd pickup. For your purposes this sounds like a better option, but as usual the costs can go to the high side.
Speaking of used, you should consider good used RVs. This can save yourself serious money. I understand that new is nice, but keeping an eye open for a well taken care of used unit is a wise option. You never know when someone has a 3-5 year old RV that fits your needs exactly. You're new to this endeavor so don't be too quick to jump unless you're sure. In addition, most RV owners often move up in size after getting accustomed to the RV lifestyle. Either save more money or keep your expenses down for your first RV.
One last thing, and it's already been mentioned, winter camping requires heated tanks if you intend to take showers. You need to understand that small RVs generally don't carry much water and showers, even minimal showers, use a lot of water. Sponge baths may be an option more often than you think. Also, keeping the tanks heated will drain your propane too. Based upon your plans for recreation during the winter you may be asking too much from your ideal RV. Not saying it's impossible, just a bit of a stretch.