Thank goodness I found this.
I made a bat file for this:
@echo off
start "GTA V" "path to your GTA V installation\No_GTAVLauncher.exe"
timeout 5
start "RAGE" "path to your GTA V installation\RAGEPluginHook.exe"
The timeout is to allow for that pause so RAGE has something to hook into. Hope it helps someone to bypass that annoying launcher demanding online, no idea if it works longer than before, but for me it works. Thanks, @darkblue!