The following is from Jim Pourroy of Fleetwood regarding a member's question about welding a tire carrier bracket to his coach near the LP tank:

When welding anything on the Freightliner chassis, the battery cables MUST be disconnected.   The best practice is to remove the negative cables first and put them back on last.   Another welding hot tip (pun intended) is to make sure that the welders ground is close to the area being welded as possible to keep the current path as short as possible.   Other important issues include welding near propane (fire concern), the future removal of the propane tank (interference concern), and possible heat damage to the chassis frame (structural concern).   Other areas to be concerned with would be the fuel lines and the air brake lines.

It wouldn't hurt to get Freightliner's opinion on disconnecting the VDC, tranny computer, engine computer, and the antilock brake computer as well as the welding location on the chassis frame rails.

You might want to consider a bolt on installation, but even that will have it's risks.