I know you've been looking for a while for the peppermint oil capsules and I was curious. I would think the peppermint oil would be really strong on your stomach and I guess that's why they dilute it with soy oil. I take the peppermint altoids which seems plenty strong to me although it has Sugar which isn't optimal but it's about the only Sugar I get so...
I wonder if you could mix the peppermint oil with something else, like raw honey or coconut oil to make it easier to go down. What are you trying to achieve with it?