roof rack questions

I need some answers and advice that I can't seem to find on the internet. I have a small painting business. I sometimes have to haul a 6 and 8 foot ladders. I've had a nissan cube for 12 years. and has been perfect.
I have yakima clamp on bars set at 42" apart. the cube is square and has a long flat roof so it has made things easy. however. i need a new car now. since they don't make square vehicles anymore, i have to be creative.
i found a wonderful company that makes ladder racks that can mount to almost any roof rack. Piggyback ladder racks. trouble is, I need for the cross bars to be at least 36" between...most of the small SUVs have rails that only give you 27-30 inches. the Venue is out (27.8") so is the Kona. if i search on the yakima site, it tells me i can have 36" spread with the 2023 Seltos. is it true? are their 'fixed' place where the bars have to be attached? or can i adjust to my liking? this is a very important detail that no one seems to know. unless i go to the dealer with my measuring tape and find out myself.