I'd add to what b54red said by mentioning that I don't have a weed or erosion problem because I use black plastic on everything. Without plastic, I seem to spend more time weeding than picking tomatoes, so I use plastic on everything. I've tried lots of things other than plastic, but the plastic is the only thing that really works well for me.
Last year, half of my commercial beds were 96 feet long and 5 feet wide (8 pieces of treated 2 x 12 x 12 long) using a wood frame, and the other half were the same size, but without a wood frame. There wasn't a noticeable difference in production.
I have tried many widths, but for me, the 5 foot width works best. A 4 foot width just seems a little too cramped to me. The plants have a little more room with 5 feet, and I can still reach the tomatoes in the center, 2.5 feet inside. I can't reach them easily on a 6 foot width, so the 5 still works best for me.
I've tried all kinds of spacings for the pathways, too. The 5 foot works well for me. Six foot is even better. When the plants bush out, there can be a foot of foliage over the edge, so by the time you subtract one foot from each side, that only leave a clear path of 3 feet down the center. However, on the commercial beds I have paths 10 feet wide because we use a tractor and truck at planting time, and also to spray the plants in the summer, and we need a trailer or truck to put the picked tomatoes in. I'm blessed to have the room to do this, but on my old beds that we worked by hand, a 5 or 6 walkway was best for me.
I'm going to try more raised beds without wood frames this year. They work fine is you cover them with black plastic and secure the plastic all the way around. This gives you stability of the bed, holds moisture longer, and makes your bed virtually weed free.
I'm going to try more beds without the frames because we can't use a tractor on raised beds the height of mine, which is about 11.5 inches. We have an attachment that goes on a tractor that is a locally made sub-soiler. It will go down over 12 inches and break up the ground very well at that depth. We can run that up and down the frameless bed, but our tractor won't straddle the bed with enough clearance otherwise. Running a gas walk-behind or a tractor tiller doesn't go down deep enough, and it takes far too long trying to loosen the deep soil on as much room in beds as I have.
I'm sure this isn't for everyone, but it is what works for me now that I'm growing several hundred plants. But I am confident that if you will use black plastic on even the smallest size tomato garden that you will conserve moisture, eliminate virtually all of your weed trouble, cut your work load down to a fraction of the time, and the plastic will hold your bed in shape and prevent erosion. Be sure to put a drip irrigation line underneath the plastic and the whole operation become very automated and much easier to handle.
Here is my Facebook site that shows pictures of a lot of things I mentioned here:
https://www.facebook.com/Home-Grown-...9172131302064/