A.B.
I had to chuckle at that, my daughter used to do the same thing! Would drive me insane at night. I would be carful if you do the plexiglass thing, if he's as curious as mine was at that age, it'll either get shoved around, taken out, or broke, heh. Mine was a climber too, could climb anything!
What i did was buy 3 of those bumper things and tied them down extremely tight, overlapping a bit. Or you could wrap a sheet up and down the bars, tieing them to the buttom of the crib near the wheels, very tight.
Both mine are so active at night time, crazy. I never used a crib for my second one, I got a playpen. Which was good cause he likes to smoosh himself agasint the soft cushy walls of it. Might consider that :) Or, just get a toddler bed! at 15 monthes I moved him to a toddler bed, took a few nights to get used to, but he loves it.
Cribs just never lasted long with me, oldest one kept climbing out at night at 1 year old.. would hear THUD, then PATTER PATTER PATTER GIGGLE TOY-NOISE haha.