Yeah, with the point skewed, it makes life more difficult, but, get er the best you can.
The spinner is the way to go, it will certainly show you if the head is way off, you will see this with no help from crosshairs or dots.
Spin and watch and see if the movement is because of the head alignment or the tip alignment (due to filing).
Certainly you can compare the flat plane even if you did do some filing. If the flat of the broadhead moves as compared to the "dot" then it is not straight.
Then shoot the arrow and see how it flies.
CHuckC