I'm in a similar boat with my Belgian Golden Strong. I could keg it, but I'd like to put some in PET bottles too for a road trip/sharing with family. I have no fear of bursting; those bottles supposedly will take 80psi without too much trouble. I've used a carbonator cap for carbing up small batches in 2liter plastic bottles at 12-16psi without issue. I'd have to think you'll be closer to 12psi than you will be to 80psi.
Nothing scientific, and I have no way to measure it myself, but random googling on '2 liter bottles psi' will garner a lot of results from folks who tested it, and some who went past 100psi without failure. 80 seems as high as one would want to go, and there's no reason any of us homebrewers should ever go that high...unless it's for a really dangerous practical joke.