since you are exiting immigration you are not strictly 'transiting'
check your bags thru to destination
in my opinion best bet is to take handcarry necessities, book a room at the adjoining airport hotel and meet your friend there for dinner, get a decent sleep and go back thru security immigration the next morning
I can imagine horror stories of people sleeping on benches & missing their flight
There are early morning flights like Scoot and cleaners with vacuums etc to contend with
The Private rest areas in The Plaza Premium will cost almost as much as getting a hotel room