There is a brand of OSB that is made with superior adhesives;
Advantech from Huber Engineered Woods. It is great stuff. It does not suffer from the edge swell as much as standard OSB. It comes in 5 thicknesses from 19/32 to 1 1/8" . I prefer it to plywood in home construction.
Edge swell is more pronounced with std OSB than with plywood, but overall plywood absorbs more water than OSB. OSB has some advantages over some plywoods. IE standard OSB is usually a more consistent product than standard construction CD grade plywood; there are no layers where 2 knots may appear in adjacent layers for example. However if we use higher grades of plywoods, especially plywoods like Marine grade, no OSB will likely come close in quality. The whole quality thing revolves around the adhesives used to adhere the strands or the plies. And OSB is meant to be a substarate; it was never meant to be painted as a finished visible component. And it looks like heck when used like that.
BTW, OSB is a very different material from the old waferboards of yesteryear or the particleboards of today. FYI, true OSB was first manufactured in 1991, waferboard came out in 1963, plywood in 1905 but the first plywood with waterproof adhesives came in the 30's with great improvements in the 50's and 60's.
For the curious here is a
link to a very good comparison with the orientation slanted to the construction trades. The author is a recognized expert in the construction industry.
Travel trailers are most likely closer to boats than to houses though, when it comes to materials and their suitability. IMO.