It is somewhat common for the front crossmember in front of the pinbox to crack. This has happened from the cheapies to the expensive fivers. Some of the manufacturers were drilling the cross members to run the hookup wiring from the truck up thru the kingpin and into the coach. Any engineer will tell you that this is a no no. Repair normally does not require removing any walls. The front cap will normally come off as well as the chin covering. Mine gave started flexing by about 1-1/2 inch while in Alaska. The repair took a week of time and consisted of removal as stated, replace the 2x6 in front of the kingpin side panels as well as the one behind it. They sent new cross members from the factory that were about twice as thick as original. All bracing between these two were replaced as well as adding gussets in the area. 35,000 miles later all is still good. Thankfully Carriage covered the entire cost even though I was two years out of warranty. A Newmar, NuWa and Teton had all shared the same repair bay for the same repair as mine within the previous month. So, this can happen to us all.
2003 Dodge HO 6 speed Laramie Dually, Jordan controller, RDS fuel tank, Air Ride 25K hitch
Carriage 36' fiver, Onan 6500, Prosine 2K inverter, 3 slides, MORyde IS and Kingpin