Hi Jim!
Brilliant idea! However, I believe it has been done already, which makes it no less brilliant.
Before leaving on his tour, PhilB posted this idea also, here:
http://www.thorncycles.co.uk/forums/index.php?topic=4230.0Unfortunately, I think he removed the photos that showed it in his album. I'll take a look and post a link if I find it.
I agree with JulianK's thoughts in the thread linked above; if one were to try this, perhaps it would be best to do so with a stem and stub handlebar, rather than a Thorn Accessory T-bar. Though the T-bar is welded and very sturdy, I fear the weight and torque of a supported rider could exceed its rating. I still think it is an idea worth trying ("For science!" as the rallying cry) to see how it works in practice. However, I fear putting the handholds so far inboard will limit leverage and make for a scary ride...like really narrow drops.
Hmm.
I think one might have better results fitting fold-up elbow cups and a standard tri-bar. When tired and in need of another position or wanting to really make time on my rando bike, I have sometimes held my own hands (intertwining my fingers) and wedged my elbows into the brake lever hood "pockets" and go for a largely fatigue-free flat-back aero position on the bike. It is amazingly secure, but leaves me without ready access to brakes, so I only do so on long, straight stretches of smooth road and upbraid myself for my foolishness the entire time (a sacrifice made "For Science!", I'll remind myself, when I stop to collect my knocked-out teeth) .
All the best,
Dan. (...who
always likes to see unusual, innovative thinking put forth for trial, and admires those who do so)