My son plays 14u and we often see low 80's at these PG events, and high 70's is the norm, again that is 14u.
Have you looked up pitchsmart rules? Here they are for 16u:
0-30 pitches = 0 days rest
31-45 pitches = 1 day rest
46-60 pitches = 2 days rest
61-75 pitches = 3 days rest
76+ = 4 days rest
Max of 95 pitches per day
With high 70's pitchers I would suspect you are more likely to have a 15-20 pitch inning than an under 10 pitch inning, so basically your pitchers are good for MAYBE 2 innings if you want to pitch them the next day and with 7 games....I'm sorry but you don't have enough pitching.
Let me also so IT'S HOT IN GA! You add the turf fields at Lakepoint into the equation and you raise the 90+ temp another 10-15 degrees. We legit have shoes softening and melting on some of our turf fields in GA....I'm not joking.....and your coach wants one guy catching 7 games? For the sake of THAT kid please encourage your coach to pass on this one.