With everything I learned from the test map, I moved on to the real map: a single mountain in the middle of the sea. The road spirals around it from the beach to the summit.
The plan: 5.1 km of road, 700 m of climbing and a clean run of about 25 minutes for a good player. The road passes through six biomes: Shore / Harbour, River Valley / Waterfalls, Forest / Village, Mine / Railway, Castle Walls and Snowy Summit. Each biome starts with a camp.
The road climbs steadily, broken up by sudden steep ramps. Orange ones are ramps you can still control; red ones are over 45°, where you fly off unless you hit them straight. Near the summit they reach 70°.
Before any decoration, I built the whole mountain with grey grid surfaces. That let me test whether the road is drivable, and check the ramps and camp spots, without touching decor. A test bot can drive from the start to the summit without falling.
I'm finishing the biomes one at a time. The first one, Shore / Harbour, is done: it's the colourful strip along the front of the island. The rest of the mountain is still grey grid, waiting its turn.