Growing in 4′-Wide Soil-Beds (in the dirt)

Q. I’m into setting up my fifth section of beds. Each one = 17 soil beds (18″ x 30ft). I’m challenged by land sloping both ways (main slope E-W & minor slope N-S = bed length). Anyway (going bit off issue) – I plan to plant mealies (corn) in this section. Got to thinking it may be good idea to set up 4ft wide beds (for the corn). I also, intend to convert in the future to Grow Boxes, so thought I getting the basic leveling (terracing) sorted now, could be wise in the long run. My question is – is there any fundamental “down side” to 4ft wide SOIL Beds?
Am I missing something basic & obvious?

A. Unless you can water the entire 4′ width you will need to build 2 – 18″ beds in the 4′. It will leave a very narrow “aisle” in the middle that is almost too narrow to even walk down. Weeding, etc. are more difficult that way. But if you don’t, then you have to apply water to the entire 4′, and that requires quite a bit more water. I’ve done it, and it worked alright, but it was more work. Also, the two sets of two rows are closer together than they would be in 4′ boxes, because the ridges take 3-4″ on each side. If growing vertically it’s best to plant the two rows about 8″ in from the outside edges, rather than 12″ in – again so that there is sufficient “aisle” space in the middle.