Why not? I reckon we could easily carry him on the bench. We already carry 3 forward's (Walker is a forward)
Looking at last night, Hopgood 50 mins, Walker 37 mins, Matterson 35 mins, Moretti 34 mins, Kelma 28 mins. If required, we could get another 5-10 mins out of each (that's 25 to 50 mins), no problems. While Matto/Kelma, could easily do another 20-30 mins (40 to 80 mins)
We barely have enough mins, for the above forwards.
So carrying Papalii is hardy going to affect our forward rotation, if we lose a player during the game/need more mins from the bench.