a 5x8 MIGHT work due to the fact the skis might be able top be stuck out the front some or till close to the spindles/a arms
but will come down to how long a sled you have
and IF the trailer has room up front to allow ski's to stick out and NOT hit tow vehicle when turning!
a 5 x 10 would make life way easier
and honesty both trailer will; have same weight rating most times, due to many use same axle on all these smaller trailers!, accept maybe the really small one's
IF I was buying one of these trailers I would be MAKING sure it also has the upgraded larger tires, then small thin /skinny one's
have to be turning a REALLY fast when being towed at 70+ mph like so many do, and they get HOT and sticky!
and well, hot tires are more prone to damage and failures, speed makes heat,heat makes em stiicky, sticky grabs more crap and increases failure rates!
its NO fun changing a tire on a trailer road side