Dealing with dark matter halo's is likely non-trivial. While the science is still out, the most likely dark matter candidate is 15-50 solar mass black holes [1].

The idea of having thousands's of light years of empty space with the same approximate black hole density as the galactic disk, but without the dust, gas, or stars to see their effects is rather a horrifying barrier to exploring the halo stars.

[1] This is a possibly theory. It is counter to axion theory (massive weakly interactive particles) as Axions require CPT violations we can't create experimentally, and LIGO is seeing collisions of black holes in the correct mass range, and which can't be created via stellar collapse (as they're just too big). Which lends some credibility to this mass range (also it wouldn't impact the CMB so the theory holds a fair amount of water).