Sometimes a quick mouse-pan view helps.
I've set one of my stick keys to toggle mouse-pan. I use only the altimeter and speedometer during fighting and don't have much trouble in seeing them in both the P38s and the Ki84. If I get rad/oil damage and have to check temperatures or fuel status, I toggle the mouse-pan and use the mouse to check individual gauges closely, and then toggle it back off.
(Mouse-pan view also helps a lot when using AA vehicles. Toggle mouse-pan, look around the skies freely, spot target, move turret, push F1(which instantly centers view) and fire.)