Is it okay if I use a shorter dowel/post to mount the puck lower to the frame? For that matter, is there any reason I can't completely omit the post it comes with and tape or velcro the puck itself to an arm or top plate?
If you look at the instructions is must be a minimum distance from all controllers and centred. If you don't centre it or adjust the Naza assist you will lots of control problems because the Naza controller and GPS antennae work as a unit for attitude and position hold.
Is it okay if I use a shorter dowel/post to mount the puck lower to the frame? For that matter, is there any reason I can't completely omit the post it comes with and tape or velcro the puck itself to an arm or top plate?
Yes, it does say to elevate it in the instructions. In reality this is not the case. Not using the naza anymore but the principle is the same as my current SuperX. I have mounted my puck on a small platform off the back so there is no interference from other components and it seems to work better than when it was on a post. I tried it on an arm first but there was interference from the esc wires. The only way to tell is to try. Just keep it close and low to the ground.
I have seen many MR's fly fine with puck directly mounted to the frame, on my Disco's I have shortened the rod to about half the standard height with no problems after hundreds of flights.
My F330 has the puck on one of the arms. It is not velcro'd but stuck on with double stick tape. Works fine. I have also done the same on my F450. You need to make sure that you minimize your interference.
I have put it in several locations dependent on battery location. if you locate your battery on the top plate then use the gps stand to move it up and away. make sure to twist your battery wires and wrap with aluminum duck tape on high amperage copters to stop the compass from getting pulled one way when you accelerate it. if you are locating your battery on the bottom then it is fine to put the puck right on top of the center plate. I have my 2.4 ground station mounted directly under my gps on a F450 and I have rock steady gps hold and no acceleration yaw.