Greens of some kind are always a good idea. What about sweet potato? Eggplant? Green beans?
You are thinking big with those veggies! Rememeber, container plants need to be those with shallow roots, the ones I find work well, and grow quickly, ideal for a traveling garden, are lettuce, radishes, beets. Small mini carrots do well in containers and have a shorter growing time. Rememebr to put holes in your containers for drainage, we made sure it was well drained before putting back in side for traveling, and we set it on plastic. Your idea of a planting medium other than soil to keep weight
down is a good one, I used planting soil, which does tend to be lighter than garden soil.
I'd love to hear from anyone who might be full-timing and has experimented with growing anything, flowers, veggies.
Anne, share some photos if you do your mobile garden!