Not quite there yet, but my Sonex requires me to measure the distance from the tip of the spinner to the main gear axle (taildragger). What is the trick to making an accurate measurement? I can drop a plumb bob from the spinner, but if I draw a line out to the width of the airplane, I have no idea if it's perpendicular to the centerline of the a/c. If I measure the width of the gear, that could be off because the gear leg distance might be more/less depending on "spread" of the gear legs at any one time.

Sorry if I can't articulate this clearer.

Thanks for any input!