I am hoping to have my observatory's foundation and piers poured soon. All of my equipment is in storage very far away so I am not able to set it up and measure the exact height of the cement pier that I will need. I wanted to pour both the cement base and cement sonotube at the same time. I was thinking of just using an extra tall sonotube to make sure that my bases are covered, but then only fill the sonotube 1/4 high with cement while doing the initial pour. After getting my equipment and being able to determine the exact sonotube height that I will need, then I could cut off the sonotube and finish filling it with cement to the right height. At that time, I would also plant my pier plate bolts (J bolts) into the top of the sonotube.
As long as my sonotube was well filled with rebar, wouldn't it still end up solid enough if I finished pouring the rest of the sonotube at a much later date? Or is this just a plain old bad idea?
Thanks for any feedback that you can provide.