I'm not a LP member but, 4 years ago I wrote a letter to the editor of The Washington Times who informed me it had been chosen for publication, but then some big event occurred (I can't remember what) and my letter was bumped. I intend to resubmit my letter soon.
My argument was/is that the rules of presidential debates should read something like this, Every candidate should be included in the debates who is on the ballot in enough states such that the Electoral College vote totals for those states equals or exceeds 270, i.e. all candidates who have a theoretical chance of winning.
In local and state elections, all candidates on the ballot should be invited to debates.
That’s reasonable but I would say even if it’s not theoretically possible they should still be in the debates so we can get all ideas on the table.
If I could set the policy it would be any candidate on a ballot in any state. That might not be practical though, I’m not sure how crowded that would make it. Your approach might be better and would at least see the Libertarians and I guess the Greens and maybe the Constitution parties in the debates.