Not sure if this is what you are asking but paper wallets aka bitcoin cheques work great.

Make a few dozen and put 0.1 or 0.02 in them or whatever you need.  When it comes to paying, just hand it over.  

If you like, you can keep a copy of the key and tell the storekeeper they have 1 month or something to transfer it after which you will yank it back.  

Or don't even bother to keep a copy.  It depends on the amount and what you want to do.  

The storekeeper keeps it with a receipt / record like any sale by any other "cheque".  One can even write name / license number / address / whatever on the back of the paper wallet.  
If there are later problems, the storekeeper can find you and you can figure it out.    

To spend / cash the cheque of course the shopkeeper need only get online, import the key, and send to own stash / wherever.  

Of course for the case where you are serving dozens of anonymous mountain climbers in your mountain hut outside of internet range this procedure will still have some problems.  People will hand you random strings of digits and claim they hold coin, then they will disappear never to be seen again.  One possible solution is a relatively recent copy of block chain (updated once a month or so?).  This could be taken out into the mountains and then used to scan people who try to pawn off paper wallets on you.  

On your brochure:

"For payment please bring a paper wallet or bitcoin cheque totalling 100 millies which was loaded before June of this year".


This isn't so hard folks.  People want to do business.