Any tips for working on single wides?

I need to add a recepticle in the toilet area of a modern (2022) residential single wide building, connecting to a light switch a few feet away. Normally I'd just go underneath and look, but everything is covered by bottom boards!

My first inclination was to grab a long drill, drill down and through, and see what happens - but maybe that isn't the best policy, lol. Any advice for things to do, or not do? What are the best practices for running and suspending the cable underneath?

Thanks!