Trijicon makes a ..sort of really open peep, to the point I wouldn't call it a peep at all -

Or there is this one, with a notch and peep option, if you left it on the notch setting it might be what you're after. It's made by WeaponSolutions.

Troy makes some of the best after market irons out there IMO - you may find the diamond aperture more to your liking, it's far wider and easier to pick up the front sight. If you look at them, you'll see that there is an "open" rear diamond option if you flip it, look closely at the picture of it, you can see it's almost like a diamond/notch combination, which may work for you also. Pics here -
http://www.at3tactical.com/collections/troy-iron-sights