That's is what I usually do^ Except first I drive my GP up to the wall to mark the horizontal line level with the center of the headlights, and then I don't level them vertically with the tape line you make, I adjust it so the top cutoff for the lowbeams are about 3 inches below the tape, gives good visibility and no blinding other drivers.

I just did it to by buddy's Jeep as his lights were aimed so high that they acted like high beams (luckily his lights aren't very bright to say the least), and since his Jeep only allows EITHER low or high beams not both (I still don't understand this design, maybe insufficient electrical?) his high beams were literally just aimed into the trees... ?!

And whatever you do, if you get brighter headlights, even if you have the urge to do so, don't get anything but halogens. HID's filaments are in a slightly different spot than halogens, so you get a horrible light pattern and blind drivers, damn trucks in my area do that **** all the time. That's when I get 'em with the LED tailgater switch If you ever go HID, do a projector retrofit.