Yeah, TT thread!!! Here is a shot from our state TT. 40km, flat course, ran 57:08 this year on a decent but not great leg day. Power right around 250w average for this distance. For 10 miles I can get to the high 260s and on a flat course, no wind will run under 22 min (with the bike as shown).
Juan - using the same bars / extensions as you and here is how I have my computer set up:
Just a piece of delrin rod cut to size and rounded on the ends. The Garmin mount just sits on top of the rod and a couple wire ties keep it in place on the extensions. I've since moved the computer up so it sits right between my hands which makes it very easy to view even when going all out.
Also spent time mitering the rod so it fits nicely between the extensions. Can use cheap PVC pipe for this or go nuts and get some carbon fiber tube. I'm tempted to epoxy the Garmin mount to the rod eliminating the rubber bands.
This was last year's set up but just to show the computer placement. I've since gone to Di2 (full internal wiring with battery in the seat post on the P3C) and just received the new 3T Brezza Nanos which will go on this week.
In terms of pacing strategies, there are some interesting studies on this. I tend to shoot for even pacing but there is an argument for shorter races that say a "U" shape pacing effort is faster and more natural. Hardest thing I had to learn was to not go too hard the first 5 minutes. Nice thing about TTs and a power meter - you can try many different variants and see what works best for you. Power never lies about your effort.