I have most of the past 30 years in "developing nations" (PC) and have seen many examples of these types of repairs. They were born out of necessity when no other options were available or possible. I wanted to believe this particular "hillbilly welding" job was driven by economic necessity rather than ignorance but I'm afraid the latter is more closer to the truth.
Evidence of such is that the PO that did the "repair" did not understand basic AS design principles. The wheels support the axles which supports the frame which supports the floor with supports the shell and all tied together with the C-channel, belly pan, banana wrap, and rivets.
The rear of the AS had OSB and plywood "installed". The problem is that the OSB and plywood was laying on top of the frame and the edges were not in place under the shell.....so the rear section of the AS was unsupported. This evidence is manifested in stress induced rivet head loss in the rear interior panels. I'm certain with additional inspection we will find other stress and fatigued areas on both the frame and the panels.
The old AS is like an ecosystem....everything is connected and serves a purpose... if one component is compromised it has an adverse effect on all the other components... and like an ecosystem...if the warning signs are ignored...the system will eventually be stressed until it fails.... It's never the big things that initiate system failure but rather the small things that are not always overt...such as a rivet...a shock...a seal...wheel balance.....etc.
It's like the old proverb-
For want of a nail the shoe was lost.
For want of a shoe the horse was lost.
For want of a horse the rider was lost.
For want of a rider the battle was lost.
For want of a battle the kingdom was lost.
And all for the want of a horseshoe nail.
In the case of the AS we can substitute rivet for nail...
In the case of our 59... an initial system failure was exacerbated by human failure... Time to get this 59 sorted out correctly...lots of work ahead...