We did this exact paddle in 2014 with the Greenway Challenge except we ended just a bit further, parking our cars on Old Millville Road where the river turns 90-degrees. Total distance was 3.5 miles but very interesting. I do not remember overgrowth unless you don't make the correct direction decision and head down West River for a stretch. In Sept. there was low water at times. One note that the broken dam just south of the Stanley Woolen is doable but should be scouted depending on water conditions. I have been wanting to do this paddle again for 10 years but might not be available in early May. Can I convince you to consider later May, let the angry Spring waters calm a bit over the broken dam and have a bit warmer weather?