Hi,
Redfield used to offer a really neat peep sight attached at the rear of their bases, both one or two pieces bases.
To me this is one of the best solutions because it can be used not only in Redfield bases but in any other. I have mine (I bought in Ebay an old Redfield base for a rifle I haven't only for the peep sight that came with it) and put in the rear face of a Warne base. Perfect. Is incredible such a small piece, with windage and height adjustments, rather elemental but it works! And is unobtrusive even with a scope in.