It's definitely much easier to line up improper with Larks and Robins. Rather than saying who's on the left and who's on the right, I have partners hold inside hands and wave at their neighbors — if you can wave with your left hand, you're a lark! If you can wave with your right, you're a robin.
In ye olden times when the majority of dances were done in proper formation, to get improper you would line up dancers normally and have the ones cross over. I think in this modern era it makes sense to line people up improper (as dancers in our community are accustomed to) and then — get this — just have the ones cross over. It's no harder than it's ever been! Just reversed.
If your community is already dancing with Larks and Robins, there really isn't any need to bring up gents and ladies.