If you want to ride a flat road in an aero position at any speed you like without traffic... head out to Heckscher State Park and ride the outer roadway. With the wind that kicks in at 20-30mph you get a GREAT workout and it will help you with your aero tuck. :-)

That MUP is nowhere to be riding a road/tri bike unfortunately. I gave up on that path a while ago because it's too unsafe.