I did the ODNO thing for a few months before getting my current lower watt halides. I used 2 Corallife CF ballast that came out of a 260watt fixture to drive 6500K T8's I bought at HD for about 4 months. Each lamp was driven with 65watts with no fires, burnouts, exploding, held up very well and were extremely bright too! The only reason I stopped was because I went back to halides and I still got the lamps. I also applied the full 130watts to 1 T8 lamp but couldn't see the difference.
I tried a 40watt magnetic T12 ballast to drive a 18watt T8 lamp and it too worked but it got ridiculously hot :icon_eek: and stopped using that after a day because did not trust it. I ended up using 65watt but it wasn't as bright as I thought it would be, the same as the 40watt mag actually and I did that for about 2 months...no issues.
Wiring the electronic is easy and you seem to have the idea already just follow the diagram as if you are working with the correct lamp. If you are doubling up the wires 'basically using a 2 lamp configuration for 1 lamp' combine the like wires or wires that go to the same side and again attached as if you are working with the correct rated lamp
The magnetic was a little more tricky...I forgot what I had to do to make it work but I wouldn't use one because of the temp
