I just went with the ascended clones and it worked out fine for my playthrough anyway. I only gave them intelligent, so no negative traits to worry about. I also went materialist and fanatic militarist for even more tech boosting and fire rate. I pushed through the Supremacy tradition first (which I never do) for even more fire rate. Went with No Retreat, which again is something I never do lol. And the first stage of cybernetics for a little bit more fire rate. All to together Clone Admirals can get over 100% extra fire rate, so it was like having a fleet that was twice as big, as long as I used long range weapons and fired first.
For extra pops I just bounced my envoys around getting migration treaties. And with pushing tech it wasn't long before I could start making gaia worlds, so no negative effects from pops who migrated in. And for those that migrated in, they were all set to residence (so not sure why they'd want to join my empire lol). Had everyone set to decadent lifestyle, so even the residence had a 10% happiness boost in total. Also used the masterful crafters civic to help offset the extra consumer goods being used up from the decadent lifestyle.
For the vats, I just kept 2 on the home world, put two more on another world, and one on a third world. I never bothered to move them around. I think the hardest part for me was in the start, the clones grow so fast I was having trouble coming up with enough minerals to keep building so they'd have houses and jobs. But after that settled down it was more like a normal game, just with really OP Admirals.
I haven't tried the Clone Fertility route yet. Just seemed like that wouldn't be as fun tbh.