IMO, no those two skimmers are too weak, even combined, for 150g of water. But I am a fan of high skimming, so take that into consideration. I am also not a fan of those two particular skimmers, some of the worst on the market IMO.

It is possible to maintain a tank that size with those skimmers though, just not that easy. It depends on your bioload, frequency of water changes, and whether you run a macro algae fuge or not as well.

Adding 5 fish into 150g of water should not spike your ammonia and nitrite levels if your have a cycled tank with sufficient filtration. (rock, sand, skimmer)

I just added 9 fish to my 180 at once with no spike.