Josh,
Track Mounts are popular with Great Lakes fishermen. The two companies that make most of the track are Bert's Custom Tackle and Pursuit Sports. The track is around 4 inches wide and made of annodized alluminum that throughbolts to your gunnels. The actual rodholders and other accessories - downrigger mounts, tool / cupholders, etc. slide in to the tracks. Several companies make accessories that fit in the tracks including Bert's and Pursuit.
Cisco Fishing Systems is located in Cleveland Ohio and make the best rodholders I've used for Great Lakes walleye, steelhead, and salmon trolling - but I'm thinking big tuna would be too much for them??? - you are going to want flush mount holders like Lees I'm thinking but then again I've never fished for Tuna. Salmon trolling is done at a max of 3.5 MPH and usually much slower. The Cisco Rodholders and the ones from Pursuit and Bert's do a fine job for salmon up to 40+ pounds which really slam the rods and make the reels scream - but I'm thinking that Tuna is just going to be asking too much??? Cisco used to make their own tracks but now concentrates on making the rodholders rather than the tracks. I've used Bert's, Pursuit, Cisco and several other companies track mount holders.
There are some pictures posted on THT (linked below)of the way my boat WAS setup with track mounts and Cisco Fishing Systems rod holders. I've since removed the tracks and have a gimbal style holder from Cisco. The track system was VERY functional but when we put my boat up for sale the dealer suggested restoring it to original condition by removing the tracks and installing Lee's flush mount rodholders.
http://www.thehulltruth.com/photos/s...&photoid=14069 http://www.thehulltruth.com/photos/s...&photoid=14088
Steve Carlson
Track Mount Rod Holders 
