If you decide to fish Lake Washington, there is an alternative boat ramp that would be easier for you to get to and would be far less busy.
The main ramp is located on the east side of the lake in a busy area due to its proximity to Melbourne.
However, since you will be traveling south on I 95 get off at the Melbourne exit at Rt 192.
Head west on 192, which is a divided 4 lane highway, proceed west about 2 miles, on the left ( east ) side of the road, look for
Camp Holly, which is a bar/restaraunt and air boat tour place.
There is a left turn spot just past, allowing you to enter their parking lot.
They have a good ramp, but no dock for a small fee.
You would be on the river, about 1 mile south of the south end of Lake Washington.
So go left under the 192 bridge for Lake Washington.
Or, go the other way, (south), and you will soon come to Lake Sawgrass, and a bit further little Sawgrass.
And you can go further, and further, with no other boats.
Be carefull as you go, as there are some shallow spots when you get past Sawgrass.
You should get a Florida Atlas which shows all the roads and lakes in the entire state.