35' 5er is easily done with 4 buckets of soapy water & brush rinsing top to bottom a section at a time.
The waxing is where the work can get serious depending on the condition of the fiberglass & the product used.
There are lots of products which will look good for the short term. It takes as much labour to use a cheap product, which does not last long, & the expensive product which will last months longer & take less time the next time around.
I do mine once a year. It takes a full day. 6 years on, the trailer looks almost factory new. Only the best marine product is used. My wax of choice is Meguires Flagship, a pure wax not a cleaner wax.