I produce a hardwood panel that is 3/8" in thickness. I'd like to add a 1/8" tongue and groove to the long edges. The smallest shaper head set up I find is 1/4" which I'm pretty sure will not leave me much meat left.

I know I can get a custom complete head made, but I'd prefer replaceable inserts if possible. Any of you folks know if such a thing exists? Of companies I could pursue?
I've searched quite a bit but so far have run into dead ends.

thanks,
Jeff