I mocked mine up on the bike prior to sending RYCA my tank and they fit fine. You can adjust the clip-ons forward and back so that they don't hit the tank. In order to clear the tank, you end up leaning a little more forward than I would like but its actually fairly comfortable.

A way to visualize this: the forks don't hit the tank, and the clip-ons are on the front of the forks, therefore...

I emailed them about the same thing a while back and never got a reply.  

does anyone know where to get 38mm x 1" clip-ons?

Ordered the handlebars and asked about a seat and seatpan. Trying to do the cafe racer thing on the cheap. I figure the handlebars and new seat will give the stock bike a good look until I can do things like worry about the rear shocks, lowering the front, new grips, exhaust, lights, mirrors and such...

The best clip-ons I've found are Tarrozzi, available from fastfromthepast.com.  38mm is available.  They are available in several offsets and heights, and they are adjustable for angle.  Most other brands are not.  Cost is $120-130.

Ryca uses Tarozzi rearsets, which are also available from this site (though not Ryca's rearset bracket)

http://img31.imageshack.us/img31/7989/imag0056sk.jpg

Did this last Friday. Makes the stock bike look a ton meaner. Ride is a little more forward, but it's not uncomfortable at all. I need new grips and bar end mirrors. I'm also looking for a new tail light and turn signals for the back, I wanna remove the chrome pieces on the fender and mount smaller lights directly to the fender. New short Ryca cone exhaust also. I wonder if that K&N air filter would fit straight in without having to modify anything.