I'm not going to claim to be an expert on the interior seam tape. I will say that I worried about it for a bunch of the build, as well as during the decision process.

Don't sweat it. It isn't the most fun job in the world, and often not the neatest, but it's not all that hard, and no one will ever see the ugly parts. Pygmy's done it that way for years, as have all the strip builders, so there are a lot of tips floating around. Pick a system that sounds good and have a go!

My favorite (OK, the only one I tried) was a combination of the pygmy syringe-on-a-stick and a bit of wire shaped into a 7 on the end of a stick. Worked like a roller frame to roll out a wet roll of tape, then the point could poke and jab the tape around to finish up. Not perfect, but it worked.