without having to combine 100 tilted ramps or some shit
That's the only way to do it besides using prefabs like the one sitood posted.
It's not very hard though. You just make a ramp, copy it, rotate it 5 degrees, zoom in as far as possible and align it off-grid with the previous ramp's edge. Then copy the previously rotated ramp and rotate it 5 degrees again. Rinse and repeat. Some people use more than 5 degrees since they are lazy but you shouldn't go over 10 degrees per ramp segment or the ramp will suck dick.
Convex ramps work the same way as concave ramps, you just have to cut off the overlaps with the cutting tool.
Also
never resize a surfing ramp or it will get fucked up.