The automatic changeover is also the regulator. If you want a high pressure connection to your Weber, (which is what your Weber expects) you are going to have to plumb into the line(s) between the tank(s) and the regulator. Too problematic, in my opinion. You'd have to tee off both tanks because you'd never know in advance which tank was full.
Much easier to tap in after the regulator. You can tee off anywhere, but understand, that you now have low pressure gas and you need to remove the regulator from the Weber. There are numerous threads on this forum and elsewhere on doing this. You can't have two regulators.
Just get a small refillable tank and be done.
