So I understand there is a slight margin of error when you accidentally bump something (I do it all the time with my range ruler when I am trying to make sure my squads are in distance 1). I was wondering if any one else will move a squad, measure distance 1, and then declare that they have a shot for next round, to prevent losing the attack just in case a bump happens and your opponent, or you, by chance place a squad or ship barely outside distance 1.

I know this isn't formally written in the rules anywhere, but I try to practice this to keep the game fair.

Thoughts on doing this in a formal setting?

In our area this is quite common that both players acknowledge that the squadron is in range and also if a ship has another ship in double arc after completing a move. Then next round or during the next action in case something was bumped it was acknowledged to be that. Sometimes this is done for ranges but usually not cause that can cause a bump.

It is not covered in rules but a courtesy in our area.

Yeah, it's pretty standard practice, and is a good idea.