It's time to get my nerd calculator out as I will take an order from you.
First of all 800 fill down is really 800+ fill down and usually averages around 840 fill.
You're square inch tube for a 63" length is 605 square inches so you are over-filling the tubes.
To fill the tubes as prescribed, it would only take .75 ounces for each tube.
If you are using only 7 tubes, then your 8 ounces of down will actually have 1.15 ounces in each tube.
What I will order from you, if you are willing is an 8 tube width, (23.5") and 40" length with .6 ounces of down in each tube.
This will come out to 13 ounces.
Even less with the lighter tape!!!
Also what are the differences in weight between the 2 tapes?
So my question to you is if I am saving you almost 2 ounces of down, will that make up for the extra tube?
So basically put, can I still get it at the 2.5 X 40" = $100.
If so, then sign me up for an order.
That's $100 for a (what will be) a sub 13 ounce pad with some serious R-Factor!