Easements, Project builders, Custom designs etc

Hi Internet strangers..

Wondering if anyone would be able to give some input.

We are attempting to build a dual occ (duplex or detached) in NSW and at a cross road of if we should go through a project builder or private builder.

Would have loved to go through a project builder for simplicity (and price) but we have a bit of a complicated corner block with a drainage easement that cuts across one frontage and to the back fence so we really aren't going to know what gets approved until we talk to council.

Has anyone done a totally custom design with say a metricon or masterton? What would the price / product be in comparison to just going down the private builder route? I think we could do one of their standard designs and a second one modified but i need to but understandably i need to pay a few thousand for them to find out and give me a quote.

The other thing is if anyone has had any experience moving a drainage easement? Obviously wouldn't be easy but an engineer friend reckons the flow of the drainage wouldn't be a problem. If it were possible i am guessing at 50-100k would be about the same cost as going a custom design versus a standard design project builder ?

I am guessing we should probably just engage a town planner to go to a pre d.a meeting with council ?