Regarding the SCC plugin: I am not sure why you are looking at the tree for 1.8.18, but with 4.3 there is really only a package for 1.8.17, with 4.4 and 4.5 a release of 1.8.20 exists. I used this plugin in different environments and different versions and it was never a show stopper on upgrades for me. The last bigger change was caused by the URL format changing because of the authentication which is probably hitting you here. This was discussed in SCC plugin issues after update to katello 4.3
