0805 LED on a 0805 resistor footprint?
Yes, you can place your 0805 LED onto a 0805 resistor pad. The LED has the exact same pad size as a 0805 resistor so it will fit on the pads fine. Recommended pads are useful but when you're using a part with an established pad size like 0805, it's unnecessary to match it exactly. I've had parts with established pad sizes have recommended patterns slightly different in one dimension or another. I've never had issues ignoring the recommended pattern and using the generic 0805 pattern.

I assume Passerby was talking about if you were hand soldering parts(?). Your manufacturer should have no problem putting the LED on a 0805 pad. There's definitely no harm in taking 3 minutes to make new pads for the LED, but I find it a little unnecessary to say you need to take all those steps if you don't.

edit - somehardwareguy has it right in the comments though. You'll want to add an indicator in there so the manufacturer knows which side is which.