How to carry a trumpet?

My son plays trumpet at school.  Typically he rides his bike to the bus stop with a back pack but twice a week he must bring a trumpet with him.  Naturally adding a trumpet creates a small problem with how to carry everything.

The hard trumpet case is 20.5 x 8.5 x 6.5 inches.

Unfortunately, mounting certain racks and baskets faces some restrictions on the bike.

1. There are no mid-fork braze-ons.  
2. The eyelets on the front are mounted behind the axle and the fork itself could interfere with a strut coming from above.
3. The eyelets on the rear are quite accessible.
4. There are seat-stay braze-ons but they're tucked behind v-brake arms.    

Note that he uses this bike for fun so a more "minimal" solution is attractive.

His bike.  Essentially a kids-sized hybrid with 26" wheels.  The rear brake noodle is blocking the view of the seat stay braze-ons.  Although this suggests that the v-brakes could interfere with rack stays mounted here.  

No mid-fork braze-ons.  Note the position of the fender eyelet.

Quick release axle which lawyer lips.  The quick release contact is minimally recessed.  Note the thickness of the fork relative to the drop out.

A lot more options in the rear.

My first thought is that a porter/flat-top rack with a cargo net would work best.  He might even be able to put his backpack and trumpet on it since the total weight of both remains relatively light.  For a reasonable price, I noticed an Origin 8 front rack that attached to the front axle and fork crown.  But as other folks have noted, the overall width might be too wide for the quick release clamp.

I've seen a handful of other options that would use p-clamps such as the Raidoverks Demiporteur rack or the Minoura Gamoh porter style racks available for the front or rear.

There seems to be a few options that all seem to have plusses and minuses including price.  Remember that this is a kid's bike and we should expect him to be somewhat careless with it.  Any experiences, thoughts or suggestions are welcome.