In this context of digging a temporary cache is just unnecessary. Most stores do not mind your pack being taken through the store or if they have some sort of policy if in the ghetto somewhere, just leave it up front. Most everyone does not want the dirty underwear & socks or a smelly sleeping bag that sin a travelers pack. If & when I need to go into a concert venue, museum etc that is gonna be a few hours long I have 2 options.
I can pay the $2-$3 to store it in coat check (if I can get past initial door security /pat downs) or I can simply hide it in plain sight. Often I will have a leather-man & knife and I do not want to air my dirty laundry in front of a line of concert goers. I always carry a black trash bag & often stash/store my pack places for multiple hours this way. As concerts are really the only place where this is required in my life; I just stash it out back or near a dumpster, under a loading dock or elsewhere that a black trash bag wont stick out. On occasion I have been questioned to the contents since everyone thinks they are James Bond & preventing a bombing but I simply explain why & what the contents are. I never actually store the bag in a dumpster as dumpster divers & dumpsters can & do get unloaded at any hour of the day. But normally in an area with few homeless people, I get a few hours of cache this way. I have never considered digging a cache myself. I have used storage lockers at gyms, bowling alleys, bus stations before & used portapotties. By having my own lock I can stash my pack & use the porta john as a closet of sorts. I can lock it & unless it is do for cleaning you are safe for a few hours again or more. This also works with trailers large tool job boxes, electrical boxes, sheds, propane/gasoline cabinets & other lockable every day containers that exist & are lockable. Construction sites, trucking or repair yards, ball fields, businesses all usually have somewhere appropriate if you look. Many trailer yards will have junk trailers that need repairs or not in service. Sometimes one can camp in these too for weeks in addition to storing/locking up gear there. Having a lock is key & much less work than digging. It also looks like it belongs most times.
Many hotels will offer to store bags for guests who have checke out so they can explore the city for a few hours while waiting on a flight,train or bus. This courtesy can work if you have enough confidence to pull it off. As shifts change from the night before to the AM, few hotel staff will require an already checked out guest to prove that they stayed there that night prior. An honest approach may also work too if you are friendly & somewhat clean.
If I really had to shed weight or get rid of seasonal items I could always ship them to myself or ship them to a friend etc. When I get south in the winter I am carrying my winter parka, insulated coveralls & heavy winter sleeping bag. Most times I must hold on to this extra gear as I travel in cyclic fashion. So while I may be sweating in the south I still need to wear it to get back north to my home. Its a double edge sword & again stashing it or creatively caching it (above ground) for hours or days is occasionally done to lighten my edc if not just for a temporary respite.
