Some paddlers just pad a solid bulkhead and use that - of course not very friendly for try-outs (which might be an advantage) I have done strippers with a normal installation (like plastic kayaks) with the bolts going right through the hull. You're right , they seem to fall on the seam tape which is good since it's reinforced there. If you're worried, you coud ad an extra layer of seam tape in the inside in that area. I used Yakamas (aluminum). Just make a cautious measurement a few times before drilling. Make a template with the rail itself on some thin cardbord for hole position. If you have a kayak now, it makes your distance measurement easy by copying that.

I just coat my holes with epoxy and let it harden. Then I also use some Silacone Calk on the bolt as well at installation time.

I'm tall so I position mine so I'm on the second to last adjustment. If you buy Yakamas, you can add one more notch with a rat tail file - before the pegs hit the end stud.

I never found a need to reinforce the bolt area any extra. My oldest stripper is from '95 and never had any problems or water infiltration into the wood around the bolts.

As the other poster stated, a blind installation is nicer if you want to go through all of that.