Fantastic Idea! The visual banner is a great way of communicating with people on their daily commute to work or as they travel. To maximise the interactive aspect would some type of code on each visual element on the banner help people to access more information? This might be a bar code or QR type code that could be scanned on a phone and then accesses further information on your database.
I too have experienced a similar situation in Kenya. In Kenya there are lots of 'Unofficial' truck stops along the main Mombasa road where truckers gather for safety against being hi-jacked. These truck stops are often frequented by women selling as you mentioned.
There is also the other issue of women being pushed into other areas of work at these truck stops raising health issues and there are people working to combat this.
What about setting up a 'Safe Trading' organisation that would look after the women's interests at these truck stops? There is the potential to trade safely without the dangers of being near the road but with added support available. This might take the form of looking after each other and having a trading area where truckers can go and buy goods from the women?