Yes you can, you dont need extra parts unless the draw is to open for you. The down side is you might get some extra gunk where the filter goes after a bunch of smokes.
You can smoke without an adapter. Depending on the chamber size, it can double as a reverse calabash. But I would recommend after every 10-20smokes to clean the tenon of gunk.
You already have your answer, but I would suggest using a filter first. They were designed for the filter in the first place, and the draw might not be as restrictive as you think.