Creating a complex terrain model from scratch

I am working on a masterplan and trying to create a terrain model of a 10 acre property that does not have accurate top data available online. The property has several rimrock outcroppings throughout the site as well as a ridge that separates it from the street and 50’-60’ rimrock pile in one corner of the property that affords a view of the Cascades. The best topo data I find online is 1:24K which is useless. So unless I want to spend $$$$ to have someone survey the property, I think my only option is to guesstimate the elevation changes and freehand 1’ contour lines and use Sandbox tools to create a terrain. This is a daunting task considering the size of the property. Up to now, I have just been modeling on a flat site because the dataset from geolocation is worthless. But it’s really important to get the property at least conceptually modeled.
I am attaching the geolocation model just to show how flat it appears.
Site Topo.skp (9.6 MB)

I can already tell that sketching topo lines is not going to work. Maybe I will just try adding detail to the existing flat-ish topo in Sandbox.

Do you have Placemaker at your disposal, or is this just native SU geolocation?

Yes, what you have there is pretty flat. Sandbox tools does have the ability to push and pull the shape, but I don’t have much experience with that. They have demonstrated it in past livestreams.

What kind of detail do you want to add? And how do you think they will help you with your project?

You could use a drone to photograph the area or just a camera for certain details and then with a photogrammetry software to generate 3D models of the land or just certain details, and integrate them into the existing model. They will contain more detailed information.

Or maybe it’s enough to add some details just by looking at some pictures of the area, sculpting the terrain with the help of the Artisan extension?

The Artisan extension may indeed be helpful for my purposes but I do not want to purchase a tool for a one-off problem. It has been easy enough to add the ridge and rimrock hills by raising selected areas of the terrain. It becomes more complex around the existing house to model the sloping lawn area and surrounding rimrock. My purpose is to just have a rough conceptual model that is useful for visualizing various additions around the property - barn garage and added driveway, new trees, paths and landscaping, decks, tiny cabins, etc. This model will not be used in any official capacity, so I am not worried about accuracy.

Sandbox tools is what I usually use for quick and dirty things like this, the other option is to use lines (maybe via plugin to make brazier curves) and I just approximate the landscape. I then usually give it depth so it becomes solid and then I can use the solid tools to subtract foundations / paths / etc.

This was a simple one for a render, recently worked on a home with walk out, terraces, etc.