Aberration boss-path of least resistance

[Sarin]

So I'm thinking ahead and planning my Aberration adventures. I never played the map on ASE, so I'm not sure what to expect from the boss. But I won't have as much time as I'd like, and I hate the slog of mutating various dinos. I even brute-forced all three maps on alpha with good rexes, rather than having to breed theris for dragon and wyverns for manticore.

 

So what would be the fastest way to make a dino army to take down alpha Rockwell? Mutate Rock Drakes? Spinos? Try to make a Reaper army? Or something else? One thing to note is that I'll be bringing over my character, level 150 and very good gear, although my flak armour is still somewhat lacking. Capped (755.3%) pump-action, though.

[MirageUK]

Nice shotgun!!.. 

When we did it on ASE we were mounted on the shoulders of Gigantopithecus running around blasting the tentacles with shotguns. 

I can't remember what we used to sit on the bridge to Rockwell to fight off anything there and munch on him when we'd killed a round of tentacles - maybe Drakes or Spinos? I seem to remember the Megalos being crap and reverting to secondary weaker attack when not mounted which was a disappointment.