Think about it like this. Set the fuse as you would normally. Now attach 4 incidence meters. Set everything (engine, top wing, bottom wing, and stab) to zero degrees.

Now, block up one end of the table 7 degrees. Everything on the plane is the same right? The only thing that has changed is that all of the incidence meters will now read 7 degrees instead of 0.

Point being that blocking the plane up so that it won't move is a pain, so... why do it?