Personally I couldn’t see renting a power screed to do a 15 x 20 pad. Will he need the 16’ attachment to ride on the forms or will he be eye balling it as most of it was done in the videos. I doubt most rental places have that long of a base. If I was going to rent something I might rent a bull float and uses a long 2x6 to screed it. A first time DIYer would catch on quicker with a bull float and it would do the same thing the power unit would do as far as finish.
Slight change of plan, the person who really wear the pants in our household (You know who im referring to :help decided we need to make it 35x15 instead of the previous 20x15 dimension.
So below is what my other option entailed.
Build a wood form around the perimeter. Screed with 2x4. Then bull float. No need to build any other wood forms ddown the middle as reference ? Does that sound good to go?