How to use the terrain system for a big world and z-axis up?

Currently I use rendered scenes for terrain but I would like to switch to jME's terrain system.

What would you recommend for a terrain of 80x40 tiles where each tile has a 256x256 height map. The grid size would be 32 then, i.e. each tile represents 8192x8192 units of the total terrain.

Another problem I see is that I had to switch to a z-axis up coordinate system and the terrain system seems to be build for a y-axis up system.

Do you see any chance to use the existing terrain system?