Hello and welcome to EAB!
You can download the 0.7c AGLaunch package from Aminet - its self contained and will run from any directory of your choice - you can write your own start up sequence that loads the bare minimum and AGLaunch
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I would humbly suggest an alternative to better workbench - to get you up and running quickly I would humbly suggest installing ClassicWorkbench 68k
this will have AGLaunch installed alongside a few optional boot parameters - i.e. holding down the right mouse during boot will allow you to load directly into AGLaunch bypassing a lot of Workbench memory use.
You will still need to install WHDLoad games to your set up however =)