I currently use the Panny GH4 for green screen work, and as long as you balance the light falling on your green screen and subject properly (3/4 to 1 stop over what the subject is metering at) you can get reasonably usable footage. Down-converting 4K to 1080p in order to "oversample" the luma channel has also helped mitigate (not eliminate!) macro-blocking that occurs because of the amount of compression needed to get those files onto an SD card.
Despite the elbow grease you'll have to put in during post to get cleanly keyed footage I would still recommend the Panny GH4 as a great >$1000 unit. If you can wait until mid-February when the Panny GH5 official specs and prices to be announced, you could possibly get one used on eBay or in a bundle (tripod. filters, memory cards) on Amazon for $850-ish. This should free up some of your $1000 budget to get a cheap but serviceable focal reducer and possible a basic incident light meter (so you can get those lighting ratios spot on no pun intended)
That trailer gave me chills.
Mox wrapped Daniel.2
Whoa, that's amazing! Why isn't this a bigger deal right now? Seems like going this route would be a no-brainer.
Buy or build a desktop FIRST if you don't already have one. That way when you need to do some heavy lifting you'll be covered. Your initial budget of $1000 could be used to build a reasonable starter machine that can be upgraded later based on your future needs. In comparison, $1000 doesn't get you much when it comes to laptops these days. Sure you'll get an i7 and maybe even a decent amount of ram. Unfortunately, you'll probably spend more of your time waiting for timelines to buffer, and simple compositions to render than you will actual work. At your price point laptop brand won't matter too much, they'll all be handicapped in one way or another. If your dead set on getting a laptop though I'd wait and save a bit more coin to invest in a new higher end Macbook. Windows can be a miserable OS when you encounter glitches or errors. The Apple OS runs a bit smoother and system bugs are easier to narrow down. If and when you do encounter something you can't fix you can just drop your laptop off at the Apple store. Later, when you decide to upgrade to something else a Macbook will likely retain more of its value versus say an Asus or a Dell.
I would recommend purchasing used units separately on eBay or keh.com. The caveat being that each unit may or may not come with barn doors or a stand. Regardless, these accessories are fairly cheap and are littered across eBay listings. You might also try buying units from alternative manufacturers like Mole Richardson, LTM Pepper, Bardwell McAllister (B&M), Desisti, Helix, Lowell Pro (the smaller 300w & 150w heads tend to last longer). and Smith & Victor. Arri has great brand recognition for good reason but many of the other film lighting manufacturers also made great lights that are still used today. My logic in referring these alternatives is to steer you away from the Chinese clones. Why buy a knockoff with an unproven track record when you can get a similar unit with better build quality for roughly the same price or cheaper? Not all knockoffs are necessarily bad but you really are rolling the dice every time you order one. Chances are if something breaks there isn't a catalog of parts you can order from to fix it. Most of the units from the alternatives I mentioned have parts catalogs, and if you live in a city with a film commission or local guild chances are someone has had some experience using and repairing the unit. That last benefit comes in play if and when you decide to rent your package out to another production. The units you will be renting out will have familiar parts, accessories, and operation.