“I’m kinda visualizing what you want to do: You want the ridge to lay as a feature on top of the dome? Connected like a rib?”
Similar to the example I showed you above?
Looks like you are getting it. 
I have all these trial and error projects. can I delete them selectively?
You can right click on any project in your spaces and delete them. For my experiment files I just make a new folder and dump them in there. I’ll clean up at some point.