Got the quote back. The axle will need to be replaced as I suspected. They're replacing with a Dexter #9 and we're going with a 22 degree angle. The cost of the axle and brakes
was something around $460 and the whole installation will be around $1250 since they'll need to fabricate some parts to attach the axle to the frame. The axle should arrive in around 5-6 weeks at which point we'll get it replaced. Just wanted to update for anybody who's curious.
The fellas I've dealt with at Mann's Welding in Shoreline have been great so far. They said they've been seeing more work coming in for fiberglass trailers so I think they must be getting referrals from this group. Based off of my interactions thus far, I'd recommend them for anybody in the Seattle area. I'll give a full report once the work is done.
Thanks everybody for your help.