"Out of Sight and Mind" locations in Heresy/post heresy

[Lucerne]

I'm working on a homebrew Alpha Legion warband, and a little stuck on where would make the most sense to situate them given their lore and the various maps:

 

https://www.warhammer-community.com/wp-content/uploads/2020/07/x1BCh0Lw29aSK4rK.jpg

 

https://www.belloflostsouls.net/wp-content/uploads/2020/07/map-imperium-9th-large.jpg

 

The lore can be summed up as followed:

1)During the Heresy, intentionally located in a likely obscure, but still accessible to the AL space- ideally somewhere with natural defenses against discovery, while still being technically reachable should it become necessary. Presumably set up well before the Heresy as part of the groundwork. Intended role: set of outposts, acting as a strategic reserve for the AL as well as research outposts, aka: things they don't want anyone else stumbling across. Intentionally kept back from the main push to Terra by the AL.

 

2) Somewhat distributed, so would be more than one system.

 

3)Ideally, wherever it is can act as their strongholds even post-heresy and maybe up to the current timeline. Fringe worlds or otherwise "hidden" or hard to navigate/remote areas ideal- without going full Warp Storm.

 

Post-Heresy, the AL seem to keep popping up in the Eastern Fringe but in the context of the Heresy, that makes less sense given it's on the wrong side of the Ultramar worlds and the Shadow Crusade?

 

The Halo stars are a bit too distant?

 

The other tempting option is the Veiled Region, but we already have a canonical story about AL forces there meeting a sticky end with the FW lore for the Dark Marches in that area, so there's a bit of thematic/location overlap.

 

Open to any other likely locations.

 

Any advice?

Edited July 6, 2020 by Lucerne