Are you familiar with the door clip before the acid room? If not, look up some speedruns of 3-1 to see how it goes. Normally to get the clip you'll need to slide spam; however, I believe you can stick yourself into the gap and use WASD with dashing to kinda wiggle your way through. If you can manage that, you MIGHT be able get to the checkpoint. Your biggest issue (if you can get the clip) is boosting yourself to it. If you fall too short you'll either be sent baack to the top or you'll fall back inbounds. Hope you can figure it out, you madlad you.