Wood Stove pipe - triple pipe question

I am installing a stove this weekend in a geodesic, sloped ceiling and roof greenhouse.

It's not a typical wood stove intall.

It involves a straight up around 14 feet, of my 6" single wall, then needs to go through a 1/2 inch thick polycarbonate glazing that is angled. There are wood struts a foot away that I am building a frame on.

I have studied all the kits available, and do have a guy experienced with stoves helping me, but I am trying to get as much info as possible before we start and before I start buying the parts needed.

My main questions are regarding triple wall pipe for the actual penetration.

All diagrams seem to show the triple meeting some sort of box under the ceiling. I am worried this is to close to my combustable (meltable) ceiling.

Should I run my triple a foot or so under the ceiling before connecting to whatever frame I end up going through?

Then - once above the ceiling and onto the roof, to get two feet above the peak of the roof, I need about 4 feet of pipe. Should this ALL be triple, to the top, or can I go a couple feet of triple above the roof, then another two foot section of single wall to top it out? Meaning if I went a foot under, and 2 feet over, a standard 3 foot chunk of triple would work?

Thanks for any advice!

AC