At the winter shows in Custer you can show with whatever tack you want. The martingale would be allowed. There are usually a few other saddleseat riders there.
We had a great show yesterday...lots of fun! We got 2nds & 3rds all day long out of about 7-10 horses in each class. It was our first english equitation pattern, our first horsemanship pattern, our first show riding one handed for WP. Considering that 6 months ago this horse didn't know what lope meant, couldn't trot a straight line & had his head in the air, I'm very happy with how he's turning out. Mater made me proud!