Would a Marksman/Tank hybrid work?
Would it be possible to make a ranged tank designed to go botlane with a support?
Both classes are supposed to be low mobility, low burst, and teamfight focused, so they've got a decent amount of overlap. A marksman that did less damage than other marksman, but also had CC and more health than other marksman, might be an interesting addition to the game. They'd do moderate, sustained damage in teamfights while peeling for squishy teammates.
It would be a great answer to kill lanes and high-damage supports like Brand and Lux to have a marksman that can just take more punishment than others, in exchange for lower damage output.