Probably worth mentioning as a failed attempt [10]
I’ve tried adding the 1.1.0 OpenSSL version in the same way the current UE4 1.0.2 version exists through C:\Program Files\Epic Games\UE_4.19\Engine\Source\ThirdParty\OpenSSL\OpenSSL.Build.cs and added PrivateDependencyModuleNames.Add("OpenSSL"); to .Build.cs (instead of also linking through the plugin). But that produced the same behavior/errors as manually linking through the plugin.