http://www.tigressoutriggers.com/images/NewOutrgrHolder.jpg

they come in 1/2 and 1/8 sizes, no new holes from bolts or tubes.

when youre done trolling around and you want to cast some or toss a fly, this deal would be good.

i guess the real question is will a boat's rod holder handle the stress of this unit?

i think you will find a lot of rodholders installed with screws instead of being thru bolted. i dont know of anyone that has or uses those, just from the pix they look ok. i would make sure that you have adequate backing plates( washers) under the rodholder ( like standard gunnel mount holders , they should work fine,(not sure i would run with them but that would have a lot to do with the size and style of poles you use.