I had a few questions about my rack rig via PM and ok'd with asker to post here in case others may benefit.
1) could you please help me by pointing out exactly which kits you purchased from yakima? bar lengths etc.
I went with 60"" tracks with 'capnuts.'
https://www.yakima.com/60-tracks-w-capnut-hardware.
Two things to consider, hardware and track length. Yakima offers 'capnuts' and 'plusnuts.' Use capnuts with fiberglass tops like our Westy's. The plus nuts are expanding hardware used when you can not access the bolt from underside - they are very similar in concept to 'rivnuts' and work if you are mounting into a sheet metal roof as I did on my Pathfinder back in the 90s.
Yakima offers 42", 54" and 60" track lengths. I went with two 60" kits but you could probably save some money by ordering a shorter size based on overall length - I think I'm close to 8' all in.
Bar length on my set up is 78".
https://www.yakima.com/78-crossbar-pair-2-crossbars Yakima 48" 58" & 66" lengths as well - depending on your needs. They also have an 86" length but these are about twice the price and mass as the 78". I've had my 78" loaded up with a couple hundred lbs of boats on washboard with no bending so good enough for my needs.
2) what did you choose as your span 48" ?
I went with a wide a foot print as our tops allow - didn't measure this but you need to ensure hardware doesn't encroach on edges of top where you might not have space to fasten capnuts.
3) when you say miter...did you do a 45deg so it overlaps? or on diagonal as you look down on it?
I mitered at 45 degrees with front track overlapping top of bottom track - makes for a tight seam!
4) I can see about how far you went forward with bars..as I se forward through bolts for top...how far from back? was this a good choice? no interference with lift hatch?
No interference with hatch - I am as far back as possible - make careful note not to exceed your access from underside of pop top. Similar to laying out the width, the underside is both shorter and more narrow than what you see from the top (talking about our pop top as it's constructed in multiple layers.)