Hear are a couple photos of my setup with out gear. Even with leaving my tharts in, I can self support comfortably, for at least 5 days. I made myself a seat board, and have a drop back to go under it, I can fit 4 ammo cans down there. Seat board is 1/2” with re-enforcements, but a sheet of 3/4” would get the job done by itself. Note the beverage holder, cut a vitamin bottle in half, drilled drain holes, and screwed it in place, will just get another one out of recycling when it dry rots
I have 2-68”, 2-48” rails, and 2-66” drop rails, as well as 3 LPros that I could probably part with, if it helped ya out? The 66” are a little beat up, but still work, the others are pretty good shape. Same ones as in the picture.
Congrats on the Culebra! I love mine, only draw back is that the thwarts tend to leak because of the design, so I always bring my pump. I never pull my thwarts anymore, having a 1 bay frame keeps it nice and light. I wouldn’t worry about splicing your side rails, either, the amount of torch you can put on this boat, even with it loaded down for a multi day, is way less on what a big cat with a spliced side rail would see, on the exact same joint.
Hit me up if there is any info on setting up a Culebra, that I can help with, or if you need some of the extra frame parts I have, would give ya a discount on them, if they can help ya out!