Many people are unaware that the new chestnut hybrids can be attacked by the same fungus that took out our native chestnuts. They are hybrid after all and the hybridization of plants leads to very different genotypes (suite of genetic material present and expressed) in the resulting trees and the presence of the same genetic material from each parent plant. You and I share 99.6-99.99999% DNA but we look very different and have very different immune systems. Same with hybridized (or any) plant - very similar DNA and yet very individualistic! The good news is, the hybrids will survive the disease and the expression of the disease can vary widely between plants. Using mud packs and applying them sooner than later will increase the longevity of the tree as well as reduce the transmission.
If you plan to have a lot of trees together the best plan of action is to cull the infected ones and choose cultivars of the hybrid that are most resistant. Michigan State University has a great hybridization program so visit their page for more information on cultivar resistance.
The orange pustules (pimples) on the bark in the 2nd picture are fungal masses that can produce spores that will spread to other chestnuts. The canker will be above ground and because beneficial microbes in the soil will kill this fungus. The figures in this trunk are also typical of the cancerous infection. Apparently these orange pustules are not visible in older trees - they will be covered by bark instead.
The soil/mud compresses increase the longevity of the tree by reducing the growth of the cancerous fungus because you're introducing the beneficial microbes that are in the soil (see above) onto infected trunk. The link below gives instructions as to how to create a mud wrap and how often to change it.
I recommend you also call your certified arborist to have them come out and do a soil injection with beneficial organisms - not just mycorrhizal but those involved in plant defense systems.
This information is attributed to the American Chestnut Foundation - visit their page at: https://www.acf.org/ma-ri/the-project/mudpacking-cankers/