Debates are the one element of modern campaigns and elections that should be immune to unfair advantages based upon funding and political party structure. Yet, the private Commission on Presidential Debates, created in 1987 by the Democratic and Republican parties, has created a debate duopoly that makes it virtually impossible for candidates other than the Republican and Democrat nominees to participate.
Any candidate who is 1) qualified to be President under the Constitution and 2) has qualified for enough states' ballots to receive at least 50% of Electoral College votes should be included. Those requirements alone would insure that participation will be limited to only the most serious candidates.