What are your lines of sight? IE: "Country Hills Trees" can mean that the farthest line of sight might be blocked by rolling hills or tree lines, etc....so, you cover ~ 1,000 square miles, but we can safely assume you can't see all 1,000 from any one point in your patrol, etc.
So, what's the FARTHEST line of sight from where you patrol, to where you'd need to be able to see to?
Also, it sounds like you are potentially looking for people who don't want to be found.....so, they might not be dressed in white, and in fact, might have the foresight to dress in clothing that would not give them away as easily. At longer ranges, the ANSI spec 0.25 lux on a target is 100% worthless under these conditions.
Typically, at long ranges, you need a minimum of 1 lux on your target to see that something is there at all, and 5 - 15 lux to tell a man with fire wood from a man with fire arms, etc. A man, prone, in dark clothing, may be invisible at 200+ meters with less than ~ 15 lux.
So, for perspective, if you need to see a prone man in dark clothing at 200 meters, you need a light that can put ~ 15 lux or more on him at that range.
A light's ADVERTISED/CLAIMED range is in terms of how far away it can put 0.25 lux on the target...not 1 lux, or 15 lux.
SO if a light CLAIMS a 1,000 foot range (~ 333 yards/305 meters) it means it can put 0.25 lux at 305 meters, which works out to only ~ 23,250 cd (~ 23.2 k cd).
At 200 meters, that throw works out to ~ 0.58 lux, and your guy is still totally invisible, even if he's standing up.
The TK75 puts out ~ 119,500 cd, so that would put ~ 3 lux on your guy 200 m away....if prone, he's invisible, if standing, you could tell he's there, but,, not much else.
The TK75 modified by Vinh (His killer throw version for example) is rated at ~ 300,000 cd, which would put ~ 7.5 lux on the guy 200 m away....still not enough for a prone guy in dark (Low contrast) clothing.
The TK61vn on the other hand is rated at closer to 740,000 cd, and would put ~ 18.5 lux on the guy at 200 meters, enough to probably spot the prone in low contrast, etc.
As for durability, as Vinh upgrades the light's components, including heat sinking, thicker wires, better soldering, reinforcements to switches, etc, his modified lights are more durable than the stock versions that they are based upon.
As for the size of the light, if you really only want a single 18650 sized light, the BEST throw you can get in that size is ~ 240,000 cd, with Vinh's SLUT, and close to that with even tighter beams if an aspheric beam is OK (Its a square beam shape, like a slide projector image of the LED itself).
For a stock light the limit is about 40,000 cd, for an Armytek Predator with XPG2 LED Runs on one 18650).
So, if I knew what you needed to see, at what range(s) it would help to tailor a good recommendation, but, the above should give some perspective at least to start the process.
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