You could hole saw a hole big enough in the frame rail for the O2 sensor to go through and install a steel tube through the frame and weld both sides. You could use a O2 sensor socket to install it. However, I've installed mine and didn't have to do that much. You won't be able to get the perfect suggested angle on the O2 sensor, but it will work. Mine has been in for a 1 1/2 years now. I drilled a hole and installed my bung in the collector at an angle that puts the O2 sensor almost touching the frame. The O2 sensor is pointing downwards slightly. Make sure you are not drilling into the part of the collector that has the side tube inside. When you weld the bung in, paint the welded area lightly with anti-seize. It won't burn away and will keep the weld from rusting. If it is welded correctly it will look perfectly fine. I will try to get a picture of it if I can.
Here's my junk... just a little EZefi on a small block.
