Hi Stan,
I've been working on something similar for a couple of weeks so hope this helps.
The original plan was to put a core unit plus din (see ucapps) with the pedal board. Got chatting to a local chap who does this kind of thing and he seemed to think it was a bit too much and maybe I should plan something more simple.
Feeling dejected I asked why - to which he said maybe just get a midi keyboard and attach it to that as its all done and dusted MIDI wise.
He gave me Evolution MKS 149's unfortunately one doesn't work but the other did but just had keys missing.
Anyway I opened it up and found that it had 2 lots of switches and the diode matrix to operate.
Using a dremmel I drilled samll holes above each diode and attached a wire to it then to the pedal board.
All done and dusted and feeling rather happy with myself - I came down to earth with a bump as it didn't work! arrrrggghhh
Plenty or rubbing of the head and experimenting found that it needed both switches to operate - so wired it up again and hey presto -IT WORKED!
Now i have full midi implementation without massive out lay and no programming involved .
Works a treat and is loads of fun. I also have transpose, pitch bend etc all in so can't be bad.
I did look at the new Evolution USB keyboard (the tiny one) as maybe my next project or maybe even the roll up USB piano might be an option for $20
Anyway hope that helps.
Aus