Decided to run Lone Wanderer on this melee run, but I thought I would pick up Danse's buff as a supplement, giving up the perk temporarily. Only problem is that I never seem to get to the final level. Is that the built in limit of LW? No companion buffs at all with the perk?

Any insight appreciated.

Unfortunately you had to be very far (and loyal) to the brotherhood of steel questline to unlock his loyalty quest. Its one of the finals ones. If you side with a different faction you won't get the perk.