As far as I can tell with the custom scenario builder, there is no possibility of random distribution within a certain amount of designated territories. Another player and I have been devising a template that would be best suited for such a start. To be more specific, for example, I assign 6 whole bonuses to a slot, but only allow that slot to start with a maximum of 12 territories withing those 6 bonuses. If this is possible, could someone please instruct me as to how. Thanks.

Short answer, no. (What you want is a set of territories pick-able for team A, etc. Right now you can only do this using Scenarios that are made by the map maker. You can ask the mapmaker to add it ofc. I think they can. That is all as far as I know.)

Long answers, you can do many other things ~