If by "tightline" you mean fishing straight down over the side of the boat (and the boat not moving) ... then, yeah, it's not a problem.
If you're referring to the boat moving (esp. under TM power) then the slip floats are not particularly effective because they will slide down the line, rendering your bait depth very shallow, due to the water pressure against them (& the bobber stop is above the float, so it's taken out of the equation).