That's a shame and the reason I was pulling my hair out last night!
I guess with Trade in mind, there's only few Options you can choose from :
Allegiance Filter : Select, enable all except "None", set "Apply Filter to Route"
-> this Filter will route only through inhabited/populated Systems
Economy Filter : Select, enable only desired Economies, set "Apply Filter to Route"
-> this Filter can be used to route only through specified Economies; as a byproduct it'll also avoid any uninhabited Systems (no Economy)
System Security Filter : Select, enable only (Low)/Med/High Security, set "Apply Filter to Route"
-> this Filter as well will route only through inhabited Systems (uninhabited = Anarchy) and can be used to reduce risk i.e. by restricting travel through Medium/High Sec Systems (caveat : can require increased Jumprange due to distances)
For pure Trading, it's likely best to create Bookmarks on Stations inside Systems that are part of a suitable A-B-A or A-B-C-A cycle.
Once such a trade loop is determined and Bookmarks set, merely click on the Bookmark and plot route. That'll make moving amongst them very easy and fast/efficient.
A good choice of such cycle-trading in a Ship with good Jumprange only involves 1-hop trades, so the Route plotting becomes a non-issue.
Unsure if that's still good, but it worked nicely in the past :
https://eddb.io/ (EDDB with its Single-hop, Multi-hop, Loop-Trade tool)