Design 2. Creative plot: -2,-4

This design keeps the ice at the level of the passages - but also flows that ice right into those entrances. This allows players to boat straight from their passage onto the main road. The rail line and soul speed lane don't interfere with boats. 

Very low lighting on this one. Moody tunnel through the Nether....

Design 1. Creative plot: -2,-4

This design makes use of the entire envelope of space allowed. Ice road is not at the same level as passages, but given that most designs dont allow direct flow from the passages to the ice road anyway, I figured I might get away with 'interpreting' the rules ;D