What is the size of the bottom frame tube?

I am wondering because I don't have the bike, yet. I am getting it with in a month... and I do NOT want to drill the frame of a brand new bike! I will make a larger plate with 6 holes: 2 for motor mount, then the other two for exhaust clamps. Also, I am planning on wrapping the frame with a radiator hose, to protect the paint.

My understanding is that with this front mount, the rear mount will not reach the frame..., so I was thinking that I will install longer studs, and put spacers and washers between the engine block and the rear motor mount.

I have also heard that there may be a problem getting the tensioner to stay. Is there anyone who can shed some light and give the best solution for this problem.

Thank you all!