One of the things I like about playing for contra dances is that you have a lot of freedom about what to play. As long as you meet the minimum requirements for danceable music (108-122bpm, contra phrasing) you can do almost anything. And then if you're a bottom left corner band you might want to play some pop covers.
While lots of pop music has a tempo in the right range, it's much less common for it to have the right phrasing. Without dancers who will be messed up if you shorten a section or add a few beats, pop composers have no reason to write songs with this structure. But many songs come pretty close! So the first part of preparing a pop cover is picking a song that won't be too much work.
The easiest songs to adjust are ones where there are two 16 beat (8s) melodies you can pull out and treat as the A and B. For example, here's the Hampster Dance:
I think the A part should pretty clearly be the iconic chipmunkified Whistle Stop (Robin Hood) melody: (mp3).
There are a few choices for the B, but I think the best option is the synth lead: (mp3).
Both of these are 16 beats, so playing AABB gets you once through the dance.
Let's try a harder one. Here's Walk the Moon's Shut Up and Dance:
The song has a reasonably phrased 32 beat verse: (mp3).
And a reasonably phrased 32 beat chorus: (mp3).
But if you jam them together they don't feel great. The song handles this with a 16 beat prechorus: (mp3).
This does not come out to a good length: 32 + 16 + 32 is not a multiple of 64. One way to fix this is to only play the second half of the verse (A1) then the prechorus (A2) then the chorus (B1 and B2). This is ok, but it feels a bit rushed, especially with the transition from the end of the chorus back into the verse. I do think this would work, but can we do better?
Later in the recording they play a 32 beat version of the pre-chorus: (mp3).
If we use that we now have 32 + 32 + 32, one and a half times through the dance. We want to end with the chorus, and all our existing parts flow well into each other, so we should probably stick something at the beginning. The remaining recognizable bit of the song is the intro, played first for 8 beats and then later for 16: (mp3).
Playing it for 32 beats seems like it would be a little long, but I think it can work. One way to handle it is to start pretty spare and then bring in additional instrumentation every 8 beats, with special attention to marking the beginning of the A2. So we have:
Once you have the structure, it's a matter of identifying the most iconic aspects of the song that are a good fit for your instrumentation, but as long as the structure supports the dance, the beat is clear, and people can tell what song you're doing you are 90% of the way there.