After extensive searching I broke down and asked a question

[TheReverend]

Is there a high on-slope piece for RHW. I made a bridge where ferries could get under but on one end I need to make some exits and right now if I go to 15m there isn't enough room to get back up to the nest bridge...

[Tarkus]

There's a "1-level" overrideable (FLEX) onslope, which, if you drag a higher network into it, can be converted from L0-L1 to L1-L2, L2-L3, or L3-L4.  There's also a 2-level one (allowing L0-L2, L1-L3, and L2-L4), but it's not as stable at present.

-Alex