You should have no problem. We often stack 6 high on the trailer but with these heavier bales we were at the weigh limit of the trailer going 5 high. With the 20' trailer we can get 22 per tier (11 on each side) and we have a 18' trailer also that we get 20 per tier (10 on each side). So if you went 6 high you could put 120 on the trailer easly and just have 30 to put on the truck.
Do you have a deck over?? On our car hauler trailers we can do 2 bales end to end, or 4 side by side, going across the deck so I am wondering how you get 25 per tier on a 16' trailer.
Ed