The oil pan configurations vary, the drain plug boss does not really limit oil drained. Some of the aluminum pans do, however, have gussets that limit a small quantity of oil from finding the drain plug. In those cases, a properly placed floor jack will cure this.
As was well stated by blackmercedes, "just change it."
Also, don't dare overlook the value of undercar inspection.
There is one indisputable advantage to my method, I'm not out the bucks it took to purchase the topsider.
Have a great day,