Looking good.
I have just a helm seat also. Got tired of the crew complaining so I just added a padded backrest where the "passenger" armrest is and I put an eyebolt in the bulkhead to clip a 100qt cooler with cushion there. I figure I need the cooler held in place anyways so if it stops the griping its twice as good.
btw because of the seat cushion, the cooler hinge has to be towards the centerline for this setup to work.
as for rod holders, things to know;
they come in 30, 15 and 0 degree angles. your transom one is probably 30. You don't have room in the gunnel to angle them outward. So if you put them in the gunnels they will point straight back, putting the line into your gunnel rod. Hmmm...You might be able to turn your gunnel ones outward?
You have rod boxes which limit the length of your rod holders. Get short(cheaper) ones and they might fit.
Measure THREE times before drilling.
Get the
angle right and the hole size right the first time because fixing it is REALLY hard.
Thru-bolt, 1"flat washer and lock-nut
at least one of the screws. Stainless.
Don't buy plastic. When the big fish you dream about DOESN'T take your rod, you'll be glad.