The root rot sounds like you are in the Alabama Clay.
How deep did you dig into the earth before raising the bed sky ward?
What size in inches is #10 rebar, 1/16,1/8,3/16 etc.
I have seen melons supported on nylon hose, but have not tried it, myself.
Have you made a design or maze with your beds or are they in neat rolls?
Do you grow running beans/pole bean on them.
I am thinking of making a box, two sides & a top(arbor) for running beans, to be rotated with melons,squash & gourds.
The gourds would not be planted with any of the Cucumis family because of crossing.

The root rot sounds like you are in the Alabama Clay.
Indeed, but my garden soil is quite rich. Soil tests say only N should be added. I also worked in about a pickup load of gin waste compost in the 90 ft length.

How deep did you dig into the earth before raising the bed sky ward?
Probably 6-8 inches -- used the soil from the drainage ditches along side to raise the bed.

What size in inches is #10 rebar, 1/16,1/8,3/16 etc.
Specs have it at 0.1019" diameter. It comes in a 5' x 150' roll and costs about $100 but will last for years.

I have seen melons supported on nylon hose, but have not tried it, myself.
Mine were successfully supported last year until the root rot - melons were up to 7-8". Each leg will make 2 to 4 supports -- just tie knots before cutting below the knot.

Have you made a design or maze with your beds or are they in neat rolls?
No design, just two rows 40 to 50 ft. each.

Do you grow running beans/pole bean on them.
No, pole beans in separate 50 ft double row and staked with canes. Having a real problem with Japanese beetles on the Blue Lake -- none on the Rattlesnake or speckled butterbeans.

I am thinking of making a box, two sides & a top(arbor) for running beans, to be rotated with melons,squash & gourds.
The gourds would not be planted with any of the Cucumis family because of crossing.
Interesting -- I've going for production, not necessarily looks.

Thanks for the response -- though no one was interested. Squash is doing great, cucumber OK, melons (other than Crane) vines are quite fragile and a bit of problem in training

I am using the same setup as bill-ho; the mesh is supported by 3 posts (ends and middle). The sheets work better than the rolls unless you want to take the time to flatten it out it will always have a curl memory. The whole thing is easy to store in the winter as the sheets lay flat against a wall and the posts stack in a corner of the shed. Use the fence clips that come with the t-posts to attach the wire mesh; easier than tying with wire.

I am running beans, tomatoes, cukes, squash, zucchini. Good topsoil with a little shale that helps with drainage. If the beans run long I just loop them over the to of the mesh.

I have 5 rows of watermelon (Charleston Gray) and similar pumpkin - will the hose idea work for these?