Draining the filter will make a HUGE mess. If you can access the sender with the filter installed, just remove the old sender with the new one readily at hand, plug the hole with a finger and install the new one. You'll probably only lose a few cc of oil and you might be able to catch most of it with strategically placed rags.

If it's easier to install the sender with the filter off, puncture the top of the filter and give it a half hour to drain. This is SOP for my oil changes, and I never spill a drop. After you install the new sensor, install a new filter.

Duke