I have to agree with Jakob. I spend a ton of time on the Rum in the summer time. Low fishing pressure and good pike and bass fishing. Once you make your first trip down, you will start learning the fish holding spots of the river.
One word of caution is that the Rum can rise quickly after a good storm. I keep my eyes on the DNR River Level webiste. There is a USGS survey station where Viking Blvd (22) crosses the Rum River.
I like to see the river level under 4 feet for my canoe in the particular stretch of river I fish. Last year, it was way high until almost mid summer. This year, with the limited snowpack, the river level has been perfect. I haven’t made it out yet, but plan to at least make one trip to see if I can find any river crappies. I have yet to catch one, but I have heard they are in there. It is pretty rare I can get out there in the spring time, so I am going to try to take advantage of it.
Horseflies can be treacherous in the summer.