Thermal:
For handsfree, there isn't much out there for thermal. You already mentioned the Flir Breach which could be helmet mounted (but isn't a scope). It isn't designed to be a long range scanner. It would probably be OK for the stalking part as you get closer but not the scanning part if you need to see animals at longer distances.
No Pulsars Monoculars currently being produced come standard with a helmet mount option and they don’t have a reticle. Not sure if the yet released Pulsar Axion will have a helmet mount option, but it doesn't have a reticle.
What you described in your requirements was something like a Trijicon IR Patrol 300W. However, with the Trijicon your price point isn't high enough. The Trijicon is the only option I have mentioned that has a helmet mount and rifle mount solution as an option with one thermal.
If you wish for a dual option of monocular and rifle scope, I would lean towards either the Flir PTS233 or the Pulsar Core RXQ30 (discontinued but being brought back by Pulsar). They are in your price range (around 2K) and could be used on a backup gun. They both are on the smaller side for scopes so they could be used as a scanner. Neither of these thermals has an out of the box solution for a handsfree option. I'm sure someone has made some type of homemade solution for something like this, but they would be a very bulky and heavy solution to be used as a handsfree option. You could move up to a Pulsar Trail XQ30 around your budget as well, but this is bigger yet in comparison to the other options already mentioned.
My recommendation here may differ from lots of other recommendations. I read on forums all the time guys say, "why buy a scanner only, when you can buy a scope and use it as a scanner?" My answer is because a person uses a scanner 95% of the time. The only time a person needs to use their scope is to pull the trigger and harvest your game. Why sacrifice what you are using 95% of the time with something that kind of works as a scanner and kind of works as a scope? The form factor of a monocular is designed to be used as a scanner. Personally, I would take a hard look at the Pulsar Helion monoculars. If you want wide FOV and lower base magnification, you would be looking at the XP lineup. If you want less FOV and more magnification, you are probably looking at the XQ lineup. For scanning while calling I like the XP lineup. For guys who like to spot and stalk, they probably are looking for a higher base mag and looking at the XQ. The Helion XPs are a little higher than your price point but not much. With this solution, you don't have a backup scope however.
Night Vision:
I don't have expertise in the world of night vision. However, you mentioned not wanting to scan with your rifle. Night Vision will work well for guiding you while walking etc but doesn't excel as a scanner. Since you are trying to get away from your thermal scope for scanning, I would still recommend thermal.
Here is what I would do if it were me. I would use a thermal scanner (or scope/scanner) while using it for calling, and thermal gun to shoot. I like to use a selfie stick while calling to take the wear and tear away from your shoulder and arms. For spot and stalk, I would scan with the thermal scanner, and probably have it around my neck for the stalk. As you approach your game, you are using your scanner to make sure the animal isn't awake, moving, etc. Once you get in position, you are then using your thermal scope for the kill. The choice on a dedicated scanner or scanner/scope combo just depends on how badly you need a 2nd gun? I like the weight and form factor of a dedicated scanner, but those who need a 2nd gun and don't have the budget will go with a combo.
