That is how I do it too. Use the oval tubing for your fairing, and insert a 1/8 inch inside diameter tube inside, fill in the ends of the oval tube. The foil shaped tubing originally made for R/C airplane strut fairings are perfect for our periscape fairings in 1/96. Have the smaller tube extend out the bottom of the fairing so the whole mast can be inserted into a socket in the sail, kinda like techological flower arranging. lol. Remember, the Permit class attack scope (the most after positioned mast on the sail) did not use a periscope foil shaped fairing, however most of the other masts did.