I remember back in the day, I believe the idea of an "all-star team" was a unifying ticket between the RPP and POP. The most ideal (and only victorious) one was the Tmthforu94/Dallasfan65 ticket. I'm guessing that's about the most successful model we can look at, but of course not the only one. As well, correct me if I'm wrong, but there isn't a large Libertarian-type Party presence in modern day Atlasia, is there? And there are more major parties and thus less chance of picking off moderates of other parties due to there being enough for someone of of any ideology to fit comfortably into a party (except maybe die-hard Conservatives and Libertarians of course. The Whigs are a more moderate, center-right party).
In the past, even the most respectable and outreaching tickets (like the famed Duke/Cinci attempt) have failed. Is there any way to construct a dream scenario? It seems to me that our only hope is that every four elections or so we get lucky, and I'm not happy with that idea.
Keep in mind... not that I really should be helping you but...
Tmth/Dallas won, to a degree because the fractures in the left were nasty and a lot of preferences exhausted (not to knock my Vice President, but as the Chair of one of the left parties at the time, this was a BIG part of it)... Duke/Cinci came agonisingly close to winning... and all things considered, probably would have knowing what was coming.
If you run a red-blooded conservative at the top of the ticket, you'll lose. Atlasian conservatives on the whole are to the left of RL conservatives and there is a natural left- progressive-centrist registration bias... so if you can't appeal to the middle ground and you start talking about abortion and school vouchers... it'll blow up in your faces.