top box

So, I recently purchased a 2019 ATAS and my wife and I are now planning on taking a cross-country trip from VA to CA. We'll get her a bike soon. But for me, I plan on doing most of the luggage hauling. I am completely novice with respect to accessories, especially in the adventure bike market...

I see several companies offering the pillion rack for the passengers seat. I don't see anyone moving the mounting point for the top box to the passenger seat, moving the weight forward. Is this a bad idea or just not seeing it? My thought was move the box forward, put a back rest on it...