Thanks for the suggestion Ed. That does seems like a reasonable alternative, yet their website suggest three strips are needed, rather than just two. Possibly the flange width varies from 57-62? I haven't installed the first two yet, but like you say, they would seal very well without the third.
Maybe instead of adhering to the flange, it adheres inside the doorframe up against the flange with the lip facing it. I'll also check in with VTS later.
I'm such a NUT about these minute trivialities, but it's all just part of my "affliction".