Seeking wisdom from those who have installed a lift

You might want to check the height under the gantry. I need 13 ft. to get a van up.
Drill a hole to find concrete thickness.
Where I didn't have sufficient footprint thickness, instructions recommended a 4 ft. piece of sufficient size angle iron welded alongside footpad, to spread load, - 20+ yrs, lotsa different vehicles, no drama .

Pic later