Yeah this would be a good solution. I've not tested them but my concern would be that the pressure in the tyre is not constant during the lap. For example, when you corner, the tyre pressure on the outside tyres will go up because the car is loaded up in cornering. I would think that these deflators would then let air out. When you got back on the straight you'd end up being under inflated. If they could add air back in as well then that would be useful. Not sure but it seems to me that that is what would happen.
The thing is that the tyre pressures are also a clue to tyre temperature p