Wall thickness - I'll have to measure. I ordered it at least a year ago and probably longer - don't remember what I ordered. I know it is welded and drawn and 1/4" OD. I looked on the McMaster-Carr website and they don't seem to carry what I ordered anymore, 36" long.
As to how many dead men to carry?
That will depend on how reliably they can be retrieved. If 100% retrieval then probably 3. 2 for possible use on one end - 1 more likely and 1 backup. I have never experienced a site where at least 1 tree wasn't available.
I don't think I could rely on a retrieval mechanism that depended on brute force, pulling them up. Some soils where they are hammered in, would make that impossible. It would also make digging them up very unlikely.
If the retrieval rate is less than 100% I would fall back to using a doubled length of my Dyneema guy line cord with fixed eye splices on both ends and rely on being able to retrieve the guy line by inserting driver in one eye and pulling.
As the retrieval rate drops, the number needed to carry goes up of course. Don't really know of the relationship between rate and number carried though. That would, of course, also depend on the number of sites the anchors were needed. I haven't really ever tried to quantify that, but my guess is maybe an max of 4 to 6 per trip.
So if I figure 0% retrieval rate on the dead man and 6 sites and 1 anchor per site, then I would need to carry 6 anchors and 1 backup, 7 total. If the 1/4" ss tubing could be used. 3" lengths would give a total of 2.2 oz for the 7 dead men (0.31 oz each).
It looks like you are using steel cable - true? With the cable fastened permanently to the dead man through a drilled hole - True?
Have you thought of a method of attaching guy line cord so that both ends can be above surface and the guy line cord retrieved in case the dead man cannot? With a retrieval rate less than 100%, I think retrieving the cord would be mandatory. That complicates the mechanism for attaching the cord to the dead man.