I level with slide in. Use 4 ton bottle jacks under the frame just forward of the front wheels. This stabilizes the trailer very well since much more pressure can be put on the frame with them than with the stab jacks.
I like my trailer slightly nose high and to be a little higher on the curbside so water will run off the roof on the side away from the doors.
I don't think leveling is rocket science and doesn't have to be real exact. You will be happier if your head is a little higher in your bed.
2012 Toyota Tundra 5.7 Litre DoubleCab
6 speed, 4.30 Limited Slip, Tow Package
2013 Jayco White Hawk 27DSRL
2010 Jayco JayFlight 26BH sold
Yamaha EF2000is Generators (2)
1996 Honda CB750 Nighthawk