Duplex designs for sloping block or pole duplex?

Hi team,

This is related to http://www.somersoft.com/forums/showthread.php?t=56057

I'm currently looking at land in the Hornsby LGA and some of the blocks appear to be suitable for a duplex but have a large slope towards the road (maybe 20-30 degrees). Does anyone have experience building a duplex on sloping land or whether pole duplexes are a possibility like pole homes (http://www.polehomecentre.com.au/favorite.htm)? I have emailed this company.

I would obviously prefer flat land but it can be difficult to find in Hornsby and just wanted to see if there are other options available.