drying fresh herbs and vegetables
I haven't done shiso, but I've had success drying fresh rosemary and thyme. I just lay them out on a cooking cooling rack out on the counter for a week or two until they are completely dried. Then I take the leaves off the stems and store in bottles. I imagine you try the same with shiso. I'd try to put them somewhere away from direct sunlight but good ventilation.
As to daikon, I remember in the old days my Grandma would just cut those into strips and lay them out in the sun on the ground! But that's very old school...I'm not even sure about the sanitation involved in doing that. If I had to guess, maybe I'd still cut into strips, then salt them liberally, and after the water drained out, I'd laid them out on trays and leave out in the sun and take in every night?