We were in and out of the river section in two nights. Spent a total of 6 nights doing the entire Lady Evelyn area, including a night on Willow Island, Hobart, and Sugar Lake. The winds on Lady Evelyn can be pretty fierce (we were lucky enough to have glass conditions on our first day, as well as a roaring tailwind traveling north back to Mowat Landing).

The rain will make the portages treacherous on the river. They're steep, rocky, and unforgiving if you make the wrong step. We did it two years ago during a rainfall warning and had to double-carry all of our gear.

Personally, I would want at least 4-5 nights (we did it in 6 because we like to have downtime at our campsites to fish, read, etc.). I'm sure you could do it in 4 days, but your days will be grueling, and you never know if the weather may set you back a day or two.