Clearance space for adding distance scale markers

[Jean Déraps]

I've ordered a set of the RPPs in metric (my preference), but I'm wondering if there is enough space, the way the lenses seem to be designed, to add a tape marker (using very thin tape, letraset, etc) for feet along the metric scale. By space I mean clearance for sliding underneath the part that is not cut out to show the distance scale.

Thanks

Jean Déraps