just do 100% infill only adds like 20 minutes and will be way stronger.

this should help for setting up the BL Touch:

https://www.youtube.com/watch?v=N-2Dy4xDc2w

https://github.com/knutwurst/Marlin-2-0-x-Anycubic-i3-MEGA-S/wiki/Beginner's-Guide-(English)

should be offset with
M851 X-40 Y-40
M500