Clamp on, or permanent mount you have to drill to put in?

Also, a recommended pedestal height for a 10' boat?

I purchased a clamp on base to use on rental boats.  I added a 7" pedestal and swivel seat.  The rental boats had 18" deep bench seats, so, I had to extend the clamp bolts on the base so it would fit the wider seat.  It worked great. Once I purchased my 12' jon, I mounted pedestals to my bench seats.

Ken

Clamp on.

0 inches.