UnCruel 

This is what I came up with. There's a good 2 inches / 8 cm of clearance over the tire, and nothing rubs. It's ugly, but should do the trick.

djb

Damn good job, and ugly it ain't. It's actually fairly elegant looking and you did a nice even job of bending the aluminium tubes equally .Nice touch with the clear tubing to stop scratching/rubbing.
And no matter what you think of the aesthetics, it's unseen under your tent and out of sight. You don't need to put the tent bag in a plastic bag or something? Or is the msr bag waterproof?

UnCruel 

Thanks. Yes, the bag is waterproof.

djb

handy, I kind of figured it would be if it is designed to go right onto bars.
I would watch for pressure point / rubbing spots where the two rods touch the bag, just because they are quite narrow, so "could" abraid the bag material over thousands of cycles of perhaps friction type movement. If you have concerns, you can easily put some sort of something between the two rods and the bag where you see rubbing occurs.
A small piece of foam, whatever is light and would do the job. Again, it would be out of sight under the bag. Foam doesnt absorb water and is perfect for vibrations.
Improvisation is an important thing in bike touring, and you've shown you can already think up of things and make them.
Have a fun trip when you go.

saddlesores

ugly? not hardly.
it's gorgeous!
good job.

Tourist in MSN

It is only ugly if you have put your tent up so the support is no longer covered up with the tent bundle and some non-bicyclist looks at your bike. The bikers will admire your ingenuity.

You might need to bend the bottom segments out wider if your load is not perfectly balanced for weight in the center, but that is something you could do on a trip if needed.

Very nice.

If it bounces on bumps, you might need to run a strap to the back side of the steerer tube to hold the tent from moving forward. I suggest you bring a strap or piece of cord that it a couple feet long on your trip, just in case it is needed.

You deserve the award for best DIY project for the year for this forum, but unfortunately no such award exists.

djb

oh, perhaps think about putting some layers of electric tape or whatever on the bars under the top curve of the tubes, in case even with the tubing it rubs off some of the black paint on the bars. Easy insurance.