But most of the people mentioned so far are not really lesser-known, are they?
Berwald? Schmidt? Khrennikov? Langgaard? Really? (Actually, "Really" is not one of the composers.)
How about these, instead:
Günter Kochan, #2
Clarence Barlow, #1
Wilfried Krätzschmar, #2
Avet Terterian, #3
Frank Corcoran, #4
Alessandro Solbiati, #2
And if any of those are too well known (I'm really no judge of well-knownness, I confess), then substitute
Bolesław Szabelski, #5 or
Niels Viggo Bentzon, #7 (good example of one I would have thought too well known, but what do I know?