You might consider this :
http://www.crappie.com/crappie/perso...ec-rod-holders if you don't have any objections to screwing the base plates down to the floor. But, before considering ANY brand of rod holder devices ... measure the most comfortable height & distance from your seats, taking into consideration your reach length to the rod handles and whether the placement of the holders will interfere with the raising/lowering of your trolling motor, or getting in/out of your seat, and distance from your knees.
As you can see in this picture of my setup, the left front mounting base is slightly farther from the inside edge of the bow than the right base is, and that was deliberately placed there so that I can raise/lower the trolling motor without having to take the rod holder out of the base when moving from spot to spot (under power of the big motor) : (pictured below)
The link I provided is for two 3rod Hi-tek holders, but as you can see from mine ... they do come in 4rod holder setups. just mentioned the 3rod setups because I don't know to what extent you intend to get into the use of multiple rod fishing methods. Another thing of note is that my setups have been "modified" by the addition of hard rubber knobs, in place of the adjustment bolts. This was done so that I can change the angle of the rods by hand, and not have to have a wrench or socket handy. (I've already dropped one socket overboard

)
I'm not recommending one brand over another ... just using "my" holder setup as an example. I did a "dry run" placement of the holders/bases, sitting in the seat to judge reach distance and best location for no interference with the trolling motor ... before the first screw hole was drilled. And FWIW ... my rod holders were purchased from another member, off the Personal Classifieds Forum of this site.