I am unclear as to the logistics of what you propose OP
It sounds to me like you are setting up a temporary market, somewhat akin to a charity sale in a church basement; one night only, local vendors who rent tables, that sort of thing.
There are many problems with this. If the only idea is to learn/use BTC I don't think that alone is enough incentive to draw consumers. If it is to sell goods, that's great but why would anyone want to go through the extra bother of converting fiat just for that?
It would be simple to set up your market and have the patrons go through a barrier where they get debriefed and set up with BTC- if they don't have smartphones they can easily use paper wallets... Then they are free to shop at your jumble sale using BTC... Simple as that.
The problems I see are this;
1. You will need to have many roaming agents "embassadors" if you will, walking about the market, ready to problem solve if and when difficulties and mistakes happen.
2. You would need to hope and pray that the value of BTC does not crash over the allotted time of your market. If shoppers buy BTC then see they actually have less buying power at the end, you just lost new users.
3. What is the incentive? Why should I convert between fiat and BTC, go through the risks and hassles? BTC is struggling to find it's real world best use scenario. We either need to identify and exploit that or simply make BTC purchases more desirable I.e. Deep discounts...
Maybe I'm not fully understanding your idea OP, but I think you have bigger problems to solve than how to include users w/out smartphones
There is a local event with about 50 shops for 3 hours in the evening, I am convincing these shops to accept bitcoins, and the customers can get a small discount if they purchase in btc.
The problem with paper wallet is spending the,. how will they spend on different items?
Yes we can have volunteers roam about