As long as you tie a rope around the duffle bag, attach cinder blocks, and jump into the lake, then locking yourself in the duffle bag first is perfectly acceptable.
Remember to head the boat back towards shore before jumping so no one suspects where you went.
Unless it is Arkanside, then one needs two shots as well, one from the front, and one from the back, after chandeliering themself.
What about if you lock yourself in a duffle bag?
As long as you tie a rope around the duffle bag, attach cinder blocks, and jump into the lake, then locking yourself in the duffle bag first is perfectly acceptable.
Remember to head the boat back towards shore before jumping so no one suspects where you went.