@martin,myne is not experience but ideas.Most fresh produce come from upcountry to the coast eg tomatoes,cabbages,kales,green maize where they fetch good prices while the trucks would bring back onions,mangoes,oranges and the like bk to Nairobi and upcountry mkts.
Your case dependss on what yu have in mind,your transport arrangements and the mrkt yu intend to penetrate.Be more elaborate...