I went to google and typed in the following.
Indianapolis box truss rental
Several options came up. You might even get more if you leave out the word box or substitute theatrical for both box and truss.
Since I have not had any need for box truss I cannot suggest a specific supplier.
If you are planning on flying your actors, the company that you hire to do the flying may be able to rent truss to you or recommend local supplier.
If you are flying your actors and haven't hired a company to do the flying, you should. Flying by Foy is a reputable company that works with groups of all sizes for Peter Pan.
"The best lacked all convictions, while the worst are full of passionate intensity."
- W.B. Yeats