i would bolt it all solid,i wouldnt like the idea of latches, it will still flex some but it should be ok, one thing that is a definate must in my opinion is flat steel straps about a foot long bolted diagonaly at each upright, this not only keeps the sidewalls from bowing out but it also gives a nice gap to be able to push out hay from broken bales especialy if your using a kicker, a kicker is alot harder on wagons too, definatly wanna bolt it no latches or anything, but as you say a small wagon so maybe your stacking it by hand, thats not as hard on wagons as the kickers are, but even so on a good sidehill theres alot of force on the lower sidewall of the wagon, i wouldnt trust a latch unless it was very heavy duty, if it lets go ya will have a huge mess, i always put mine together with 5/16 or 3/8 carraige bolts, that works pretty good just gota keep them tight, and make sure to add diagonal braces to keep the sides from racking back also, i didnt when i first made mine and it leaned back pretty good after a few uses, but a ratchet strap and then attaching some 2 bys running at an angle stiffened it right up