If you know where you will be staying (?hotel) before your return trip, give them a call to ask if they will hold a package for you.
I have done that. Had a poly mailer addressed and ready, and mailed it ahead when I got to my destination, or gave a shuttle driver or hostel $$ to cover postage and their time to drop it in the mail for me.

NJH's idea of having airline put it in 'car seat' bag is good too. I have and would pack trekking poles (and tent poles if you have them) carefully down center of pack (tips covered), with other gear around them, and avoid items hanging or in outer pockets - everything inside the pack. Carry-on electronics, water filter, and anything you can't fit inside the pack.