I show mine in a pony weymouth bit.
Here are some pictures:
The above picture is the "Mare bridle and bit" which you can purchase from D&S Harness (dsharness.com Dale Lutke)
Above bit and bridle is available from Ozark Mini Tack (minitack.com)
The weymouth bit has a very slight port and a curb chain. Obviously you can see the side of the bit, the reins attach below. This allows you to really get some tuck and head collection when you work your pony on the rail. I found a couple of these bits from Jack's Manufacturing for $30, but I can't find them anymore. Most places mark them up to about $50 each.
Andrea