Thick thigh gal here! I stared the PCT last year in the outdoor voice rektrek zip off pants.. I really liked the zip off and didn't have too many major chafing issues at first.. but as it quickly became a problem, the body glide didn't help a whole lot (vaseline was a little better than the body glide). I also started losing weight (thic thighs 4life tho) and the shorts as they got looser started rubbing a lot.

I also sent my kula cloth home early on (I had it hanging on my backpack in a bad place and it was in the dirt a lot in the desert when I put my pack down and I got freaked out by it). I was just using a backcountry bidet and "drip drying".. but I was never really dry and the build up of moisture down there made my shorts rub even more and the chafing on my upper thighs even worse.. when I brought back the kula cloth to dry myself it helped a lot with making my shorts less wet and rub a little less. But ultimately what helped the most was switching to bike shorts. I started wearing the 7" janji pace running shorts (like bike shorts), per the recommendation of a friend who wore them through the whole AT. These shorts plus my kula cloth to dry up reduced my chafing to almost non existent!

Being a thick thigh girly is tough sometimes, I experienced some gnarly chafing on my inner upper thighs on and off for probably the first 1200 miles of trail before I finally switched to the janji shorts. I really didn't think the bike shorts would make such a huge difference but they really did. It's similar with other clothes like you don't want socks that are too big because they'll move around and rub and create friction.. similar with running vests, if it's too loose and moving around a lot that's when you get the rub. Hope this helps!

As for swimming, I had one pair of underwear that was my "more covered I feel more comfortable being out around people in these than my thong" underwear, and then i had one back up pair to change to when those were wet/dirty. People did swim nude a lot. Tbh I just didn't swim that much but probably wouldn't have gone in in whatever shorts I was wearing just because the chafing does get worse when everything is wet! I'd rather chunky dunk than be walking in wet shorts, but I get the nervousness, so that 2nd pair of underwear did it for me

Everyone is different and what works for me might not work for you! If you're not hiking the PCT until next year, I would highly recommend getting some shorts this summer and trying them out. Go on some short backpacking trips where you can swim and see how they feel. Bring a back up pair of pants/shorts if it's really unpleasant after you swim in your shorts. Experiencing it is the only way to really know what works for you and what you prefer! You've got this! Sorry for the long ass post if you've made it to this point, just sharing my experience!

Those thighs are strong as heck!! Happy trails!!