It's pretty simple to fabricate a V-shaped piece of sheet metal to mount under the filter to channel the spillage to a drain pan. Then do the half-full thing on the new filter, and if you're really anal-retentive about it, disable the ignition and spin the engine without starting it a little to finish filling the filter and pressurizing the system. If you don't goose the throttle on startup, none of that should be necessary.
Jerry
