RV Repair: Rotted floor, interior paneling, lag bolts

Question
I have a section about 4'x2' in the floor of my towable that has rotted and delaminated the plywood. Also the outside crossmember running lengthwise between the door and front of the unit is bad. This was discovered because the lag bolts into the crossmember would not hold the awning on. How much work is it to replace a section of floor. It would be  under the front bed and fresh water tank. How do you do it. From the top (inside) or the bottom (outside)? 18 '1988 Yukon.  

Answer
Rick,
   You will need to do this repair from inside.  Remove the bed and water tank and anything else in way or mounted to the floor.  Remove the damaged section of wood all the way to the next floor joist so you have something to mount to.  You may need to add additional bracing at the sidewalls to support the new floor.  If you are going to try to remove the bottom of the wall as well you may need to remove some interior paneling, as well as some of the lower exterior metal.  I hope this helps, good luck and happy camping.

Darren