One thing i've learned through my job is that when I was applying for jobs I was doing it all wrong.
I applied at a local country club to be a cart kid / dishwasher (I was 15).
-Never got a call back
So I ended up painting that summer becuase my dad knew a guy.
At the end of summer I found out my mother was friends with the chef at the country club, and I was immediately hired.
I found out the chef needed someone the whole summer, but never got any applications. I also later found out the people taking applications were mostly throwing them out because it was easier.
I'm now a cook making much more than minimum wage, enjoying working.
The next summer instead of applying to dozens of places I walked right into a restaurant, found the chef, talked with him, and got a call back 2 days later.
When I am next looking for a job of this caliper (basically, kid work) I won't fill out an application. I will wait for a time they are not busy and walk right in to meet the boss.
Fast food, retail, small stores, etc. should (in my opinion) be approached the same way. Walk right in and talk with someone. If you come across as professional, not stupid, and make a good impression, then submit an application. They are more likely to remember you when doing hiring.
So go to those warehouses, find the people in charge of hiring, find the bosses, explain why you are invaluable, don't come across as a jackass
. Even if they are not hiring at the moment, when he fires someone he'll probabbly remember you first.
Just a thought.
I can't say this works for "real" jobs, but for the caliper of job you are looking for I think it is the best bet. Also remember it's coming from an 18 year old with next to no life experience