If you have room in your yard for a smaller tree, Hop Tree/Wafer Ash, Ptelea trifoliata, is a great choice. For the past ten years I’ve noticed that Giant Swallowtails use this tree as a host plant.
What I just noticed yesterday was that a Tiger Swallowtail was also laying eggs on this tree.
I also have a Tulip tree in my yard, which is also a host plant for Tigers, so I was surprised to see the Tiger use my Hop Tree as a host plant. I have found other internet resources indicating that Hop Tree is a host plant for Tigers.
This tree takes vigorous pruning without complaining so don’t be bashful if it gets a bit to large to your liking. I’ve also found out that there are male and female varieties of this tree. One tree has hundreds of seeds, while the other never has a single seed.
If you want some seeds later in the year, let me know. The seeds germinate easily with cold stratification.