Roof box position

I'm just about to inherit a smaller roof box which is too short to fit between the fixed cross bars I have. Not a problem as I can get some aluminium box section to interface between the two. Question is which is the better end of the roof to mount it? Forward to better use the windshield as a deflector or rearward to better position the load onto the back axle? Yes I know it's all marginal on any benefit either way but I like to do the best I can for my OCD. I also appreciate the massive improvement in mpg I am going to have with a roof box and all terrain tyres but it is for the benefit of the dogo having more comfortable traveling arrangements for the trip to Wooler.

Thanks that's what I was thinking, but it's my first roof box so I have no point of reference.

Something else has just occurred to me. Is there any reason why I couldn't fit the support aluminium bars under the fixed cross bars to keep the profile lower? I might use m 8 hardware instead of M6 just for peace of mind. Is it going to create more wind noise if the gap to the roof is quite narrow or will the reduction in frontal area help reduce that?

So my intuition has some science in it, good to know. Yes it's quite short and does look better further back. It's also better under slung as it were relative to the cross bars. I just received the u bolts so I can finish fitting it on Saturday. Pictures will follow.

This is a completely off brand one with no markings I can see. Weight wise I'll be no more than 6 or 7 kg more than I would be without the box as it is not for additional storage but for avoiding having to completely pack around the dogs cage with all the bulk items like clothing and bedding we seem to need for a week away, it's to make the doggo s life nicer.

Bolted on. Just need a spanner check and then it's a test drive see how loud it is.