I have tried that, but I couldn't get it to work. The only way I succeeded was placing a few terrains on top of each other, each with (1) a tilemap (2) a alphamap. I stretched the alphamap out over the entire terrain, so it has a low resolution and I kept the tilemap small, to give detail.
Later on, I've made a single terrain with (1) a colormap and (2) a detail map, in greyscale. The idea was to suggest a tiled terrain using different colors.
Maybe you can combine both methods, but instead of using a 2nd terrain, use a few mesh terrains here and there that fit exactly on the blitz terrain. On these smaller mesh terrains you can apply alpha, so they blend into the 'background' terrain.
Later on, I've made a single terrain with (1) a colormap and (2) a detail map, in greyscale. The idea was to suggest a tiled terrain using different colors.
Maybe you can combine both methods, but instead of using a 2nd terrain, use a few mesh terrains here and there that fit exactly on the blitz terrain. On these smaller mesh terrains you can apply alpha, so they blend into the 'background' terrain.