Has worked in the past, Chalky.
Early 80's, Steve Croft, Chris King (/Terry Sampson) and Dave Thorley, all individual promoters at the time, had an alliance whereby they agreed to not clash nighter dates etc.
I think it went under the heading of '3 Voices' or similar.
I vaguely remember going with Steve to Stafford to a meet, back in the days of Cleethorpes, Bradford, Warrington, Top Of The World etc.
It certainly worked for a while and allowed all these venues to flourish, as I recall.
Sean