First RV Purchase - Need Advice - 2002 Jamboree 31W

For your soft floor you need to figure out if it is from a leak or just fatigue. If a leak you first need to make sure the leak is fixed. If its just fatigue then reinforcing the floor from below seems like a reasonable solution. Hopefully it is fatigue and not rot. In front of the sink is a place where you sometimes see fatigue as that gets the most standing weight. Good luck and let us know how you make out.