About 4 years ago i had a tent made for my camper (since sold) that had a 1400mm drop.
I had Tambo Campers in Melb custom make it. Cost $4400, but was beautifully made, didn't look any different than the standard drop.
If your on a smaller budget then a off the shelf tent modified would be cheaper.
Or make a side folding hard floor to put tent on.