The PWC trailer should work fine......suggest running the tires at a reduced pressure since the total weight is much less than what it's designed to carry.
The wood bunks won't give, so if you use PVC pipes, I would use 2" as Tom Kirkman used years ago.
The 2" diameter pipes will conform better to the hull shape although the 3" I used seems to be fine and has not stressed the underside and deck of the hull. I keep my PA-14 stored inside my garage so the hull is not exposed to sunlight heating and potentially distorting the hull.
Hobie sells the "official hull cradles"......expensive, but that's another option.
Another wild thought I have had over the years to accomplish absolute hull support and have never seen anyone try so far, is to use high quality, double braid sailing rigging line, as in "rope slings" under the hull.......3/8" to 7/16" OD. This stuff is very strong and low stretch.
Basically, its used in place of the PVC pipes and you only need maybe 26' total...this includes line from the end of the aft support to the roller, if you use one as I have on the back of the trailer and shown in the photo.
Hobie recommends the hull have their cradles to be cross supported 67" apart......well, my thought is it's better to support a larger % of the hull as the rope would do......Yes/No????
Anyway, just a wild thought.
Maybe Tom Kirkman will read this post and chime in......he has had some really good ideas over the years and I have "stolen shamelessly from him"