are the extensions independent of the base bar or integrated?

If separate, tilt the whole thing while keeping the base bar level and aerodynamic.

if fixed, put washers under the front of the arm pad holder to tilt the arm pads and then get super big ski bend extensions to get the height for 15 degrees of upward tilt.

EDIT: OK, I looked for a picture of your bars. You need washers under the pads, and then ski bend extensions. You can play around with putting various ones in backwards to get the height.

I ordered Use Tula aluminum extensions from the UK, 50 degree ones.

EDIT 2: you really ought to do yourself a favor and a) get a good fit from a reputable fitter as your body is the # 1 cause of drag and b) if you're really fast, you should have a better aerobar, like 3T Ventus or TriRig Alpha X

---

Eric Reid AeroFit | Instagram Portfolio
Aerodynamic Retul Bike Fitting

“You are experiencing the criminal coverup of a foreign backed fascist hostile takeover of a mafia shakedown of an authoritarian religious slow motion coup. Persuade people to vote for Democracy.”