I have been down this road too.

Anyone with any system can do this. Current systems are limited to the 30 meter range, because of the current output transistors. Truth is 30 meters is more then enough for most battlefields, so the trick is to limit the range of the current systems. I have included two diagrams that will allow people to do this. It is hard to nail down the resistor for repeatability. The ohm resistance is so low that wire distance and thinkness can have an effect. So each application will require some trail and error to find the right resistance to put you in the ballpark range you are trying to achieve.

The problem is this puts your light tank at even more of a disadvantage. I can see this becoming useful if we have IR battles that have the Germans outnumber 6 -1, then to even the playing field the lighter Shermans could be forced to use a range limiting resistor. This would mean they have to move in close to kill. FF could still have the long range though

So there is nothing new about this idea, in fact we beat this up on this forum last year before the Danville extravanza. I did a whole bunch of testing to find the resistance needed.

I wish this fellow well, as he seems commited to actually produce RTR stuff. A word of caution to him though, Whatever you make, make it at least be able to play the current Tamiya style of game, or be warned you will have a hugh uphill struggle to sell any. All developers should adhere to this policy. or they risk splinteirng an already small group. IF you care about this hobby, make your design have a setting that makes them Tamiya compatible, and that your IR sensor wiring will accept a Tamiya TBU.

If HL would have done their homework they could have produced and IR battle tank that would have played with Tamya out of the box. IT only would have cost them pennies more