Frederik. You would need to tweak the Vertical Position of the gear. This can be done in FSEdit but I would recommend not using it at all. Much better to edit Aircraft.cfg manually in Notepad. Check out any default Aircraft.cfg for more infomation. The entries you need to tweak are under the [contact_points] section. point.0, point.1 & point.2 are usually the gear parameters. The Vertical Position is the 3rd entry along from the = sign in each line, (start counting from 0). point.0 is usually the nose or tail wheel.

The example below is copied from the default 737_400. On your problem plane try reducing the values in bold type. They are negative values in feet so lowering the value will lower the aircraft. Change them by a small amount (subtract 1 foot) at first to see what happens. Then exit Notepad saving changes. It's a case of trial & error until you get used to it so check it out in the sim each time you make changes. Make a backup copy of Aircraft.cfg first in case you mess it up.

[contact_points]
point.0=1,  40.00,   0.00, -8.10, 1181.1, 0, 1.442, 55.92, 0.8, 2.5, 0.9, 4.0, 4.0, 0, 0.0, 0.0
point.1=1,  -7.75,  -8.58, -8.68, 1574.8, 1, 1.442,  0.00, 1.0, 2.5, 0.9, 6.9, 6.9, 2, 0.0, 0.0
point.2=1,  -7.75,   8.58, -8.68, 1574.8, 2, 1.442,  0.00, 1.0, 2.5, 0.9, 7.1, 7.1, 3, 0.0, 0.0

Nope, no joke.  A lot of stuff can easily be fixed when you know which file to tweak and how to tweak it.

To answer your question, you could end up with a plane that's 19 feet off the ground.  But other than that, that's about the only way you could screw it up.  If you do it exactly as posted, you should  be fine.