Heck, it you are planning 20lbs , why the concern about a front rack? I sed you've now ditched the idea, and rigging up a larger handlebar bag would work great, free up some pannier space and it ain't a big deal for the handling. It'll be lighter than front rack and panniers and there are reasonable ones that aren't too expensive.
Why add at trailer, extra weight, not as easy to lift into a car trunk of pickup back if needed.
Seems to me your roughly 20lb load will work fine with adding a handlebar bag, plus you keep your valuables in there for going into a store or whatever.
Not sure why I would ever need to load it into a car or a truck so that seems like a moot point. I haven't been able to find a handlebar bag that will work with my brake set up without also changing that.
Another thought: My handlebars has a shock absorber in them. Do you think a handlebar bag would mess with this mechanism?