After we had spent several weeks underneath our van equipped with metal brushes and scraping irons we slowly gained the insight that this was very inefficient use of our time. We needed a quicker solution for this problem and after we had informed with some more experienced people, we ended up looking for a sandblasting company.
The yellow pages brought us to the closest sandblasting company we could find (about 6 km away) since our major problem was how we were going to get the bus there while it is on the trolley. Luckily we could use a big double axle trailer to transport our van to the sandblaster. It took us quite some effort to get this giant shopping trolley onto the trailer.
During the transport to the sandblasting company, we were trying to figure out how we would get the bus off the trailer. Once we got there, a forklift truck did the job for us: scary but very effective!
A week later we could pick up the bus at the sandblaster. The result was pretty satisfactory; a rust free Splitty sprayed in a primer suitable for welding.