I'm a writer.
As such, there are times when I really need to get away from everyone and everything so I can totally immerse myself in just writing. Doing this while camping is wonderful. Or, sometimes just jumping on the bike with the computer in a daypack so I can park my butt in some shady spot in a park forest is good enough.
While writing and programming share the same mental processes, they have different demands on a computer. Programming is going to be much more demanding on a computer than writing prose. The MacBook Air is certainly at the top of the heap when it comes to low power consumption, but if you are programming some pretty heavy stuff that could drain the battery faster than the work I am doing now. That could greatly reduce your working time if you are completely off grid in the woods. That could be enough to impair your productivity and nix your project.
Power comes first. Without power, nothing else will work. As mentioned above, those big, portable solar panels are a very good idea. Free energy when there is enough sunlight. On any mostly sunny day, one panel should easily be enough to keep a MacBook Air chugging away all day. Even on a mostly cloudy day, the larger panels might be able to provide enough juice to keep you going. But this will also dictate your location. You need clear access to the sun. If you are in deep forest, it won't work. This means camping in a meadow or on the shore of a lake. A plus side here is when the sun goes down, you will have a wonderful view of the starry sky above. (Great for recharging your batteries!) If you are on a lake and are inclined to fishing, there you go.
Connectivity is important to you. It is for me, too, as a writer because often I need to jump online to reference various subjects. This means, you won't really be doing any "deep forest" camping, where you are truly away from all aspects of civilization. A lot of family and national forest campgrounds now supply power to campsites. That solves the power issue. One extension cord and surge protector power strip and you are ready to get everything done while you sit by the fire. Some of these campgrounds really suck. They are overrun and poorly maintained. But there are others that are truly gems! Sure there are other people around, but I find that kind of adds to the ambience. I do enjoy hearing the soft voices echoing in the trees. The sound of distant laughter. The smell of campfire smoke wafting on the wind. The campsites in the older campgrounds are well surrounded by trees and shrubs, so you really can't see one site from the next. This guarantees your privacy and isolation if you need it. You have to hunt for these gems. When you find them, you may find them quite enjoyable. The added services do make life a lot more pleasant while camping, and you can maintain your full technical capacity without hinderance.
You can set up your smart phone briefly as a hotspot for your online sessions. If you are only on for short periods during the day, this shouldn't press your data plan limits. For those who have very heavy data needs, it would probably be cheaper to buy a cellular modem and connect to that than it would to tether to your phone.
Another mention above was to use an RV. You can use a small trailer, too. Much more economical. With a larger trailer called a "Toy Box", you could also pack a motorcycle in along to use as your get around vehicle when you want to get away from the campsite for a change of scenery. A trailer or RV offers protection from the elements. I'm convinced I am the incarnation of a rain god, as the moment I pitch a tent, the rain starts falling. It also allows for better security for your equipment. Sure, a crowbar could get past a locked camper door, but most of the losers who skulk around campsites to steal things are looking for easy pickings and don't want to work for their booty.
You'll notice that my suggestions start with deep woods camping and move closer to civilization. But how you implement things depends on how you mix these elements together. One of my cousins purchased a chunk of land up in Maine. He parked a trailer in the center of his property, connected up a solar panel and a windmill to generate power, and added a composting toilet to the site. He can live off-grid for extended periods until he needs to go to town to get food and supplies. Owning your own land means there are no problems with restrictions of being on public land or being worried you might be on private property and possibly invoke the wrath of the landowner. The only flaw in my cousin's setup nowadays is that his property is isolated enough that he gets no signal for telecommunications. He bought it long before smartphones existed, so that wasn't a consideration way back then.
Take all the suggestions and put together the different pieces that you like and try and find the right balance for yourself and your needs.
One thing I should mention about SSDs is that I have a couple of thumb drives that have been sitting around untouched for years that are still usable and the files are still readable. The only one that doesn't work is one that was sacrificed to a very powerful magnet in a demonstration of how vulnerable flash drives are to magnetic fields. So, perhaps an SSD drive will be more stable than I suspected.
Uncertain fortune is thoroughly mastered by the equity of the calculation. - Blaise Pascal