For some reason that I still don't really understand, the ideal of the "Montreal Relay" seems to have fallen out of favor with most experts. I learned to play Montreal Relay some 30 years ago, and I taught it to my wife. It just seems so much easier than all the nonsense of today's world.
For those who don't know this, it is sort of like a Puppet 1C opening, in a sense. Partner responds 1H or 1S with a 5-card suit, or 1D to deny a 5-card major. As 1NT would show 8-11, 1D is bid with a 4-card major (or both), just long diamonds (and not right for 1C-P-1D as 8-11 or so), or balanced with a range other than 8-11.
The pundits seem to suggest that this approach somehow is prone to problems with interference or something, but my experience is otherwise. First, when I play Montreal Relay, I don't ever need Support Doubles for these situations. Second, I never need to check back to see if partner really has 4-card support. Third, checkbacks generally are not needed at all. I mean, auctions are extremely easy. Imagine playing bridge where the most common opening (1C) comes up a ton, and yet I never seem to have any occasion where I need checkback, xyz, support doubles, structured game tries with pattern asks, or any of the things that usually take up 20 pages of notes. No "Kranyak Jump Reverses" to show 3-card support and a great minor. You just raise with 3 and have a fit established. EASY.
These sequences are SO friggin' easy that most of us use a short club, and most of my partners only open 1D when unbalanced. This actually creates another interesting twist -- you end up on occasion opening 1C and then rebidding 2D to show just a balanced hand with long diamonds. This happens in competition and almost never seems to cause a problem (one instance being because I made a foolish bid).
The amazing thing is that this structure works better, IMO, than anything I play with "better players." I sit down with people having 5000+ ACBL Masterpoints, and we play xyz and support doubles and 2NT game tries with unwinds and all that jazz. Pages and pages of discussions and notes. Odd situations that arise.
Then, I sit down to play Montral with my wife, who has 150 masterpoints. Never a problem with strain or level. Easy.