I stumbled on this link in search for an answer to the original poster’s question and was disappointed that there was not a satisfactory answer.
After hours of pouring over google to no avail, I finally turned to the code base and found the function that controls the filters getting set in route options.
The syntax for what we are trying to achieve is
frappe.route_options = { "DocType Name.field" : value }
So in the case of the original Poster… your code should look like this: