Hi there! I think it is excellent you want to compete with your horse more organically! You can do this barefoot. While I no longer event with my horse, when we did, it was barefoot. We now do 10 – 25 mi endurance rides barefoot on all kinds of terrain. It is a combination of diet, the environment your horse lives in ( are they stalled on a mat? Do they have varied terrain with rocks, etc in a pasture? ) and the type of trim you give you horse if necessary.
There is a really good blog out there : http://rockleyfarm.blogspot.com/ which goes into rehabbing horses that had some pretty extreme issues even in shoes to go barefoot. Many of them are competing at higher level events in GB. Give them a shot. She has all kinds of case studies, and literature on the site to read.
I hope you both find success together both in a ring and on the trails.