Recruiting scrap clients by offering bin service

I have 4 customers mainly right now that I do electronics pickups from (and one that is just wires)... I have been thinking of trying to offer some sort of offering like this to them to encourage them to keep using me as currently they just text when where ever they are keeping the stuff fills up, and I just hand load it into my pickup truck (or utility trailer depending on amount).



I have been thinking of ordering some of these https://www.uline.com/BL_1841/Poly-Box-Trucks and having enough to swap out at each location. It would just mean I need to bring the trailer everytime though as I would have no way to load them into the pickup bed when full. They also arent super cheap (but def much cheaper than full metal containers like you are using!)