I did the same for engines... if it becomes too little for the maps just add in a map modifier to the sensors so lets say insane map (MapSizeDefs.xml) give a +10-15% bonus to sensor range. There already is one for range where an insane map give +100% range. Or add a device that require Thulium that give say +25% sensor range in the late game.
You can also lower the modifier to say 8% so the fall is not as bad, but it is perhaps more intuitive to go with 5% or 10% steps.
I also like how Transport hulls are crap as sensor boats, you need at least a Medium hull to get a decent sensor ship, but the Large/Huge hull is the best.
Transport now also need more engines to go somewhere which I personally like... all transport hulls will be slow and blind... 
After looking at the math and playing with it some I might also suggest using -5% per sensor module instead of -10%, but for engines I find -10% to work pretty well. Those -5% will add up pretty fast as well...
