If you're horse isn't into ports (which my horse isn't at all) a mullen would probably be a pretty good fit. Reinsman Straight Reiner 1/2" Copper Oval Bit
This is what I use to show in. It's really mild and doesn't put any pressure on the tongue.
Another one I really like is this myler bit. Mine doesn't have quite as high of a port... I couldn't find the exact bit. They're really similar though. I haven't rode a horse that didn't go well in this bit. Myler Ported Mullen Barrel Bit by Toklat
When I work my horse, I tend to stick to just a twisted wire snaffle and some training forks. Though I ride my horse with almost only leg so what's in his mouth does't matter a ton so I like to keep the bit minimal.