Is there anyway to get both these boats on my car safely?
If there are laws that limit the length of vehicle crossbars, they likely vary from state to state.
35 years ago I had 78" crossbars on my Ford Taurus sedan, specifically so I could carry two tandem canoes side-by-side. No one ever complained or gave me a ticket. And, as a practical matter, the vendor of the bars had no idea, nor was it their business, what vehicle(s) I was using the bars on. I'd just buy a sufficiently long bar and tell them if they're nosy that you're going to take the bars home to put on your big pickup truck or van. Then drive around the block and install the long bars yourself. What's probably going on is that the vendors want to avoid any "legal liability," real or imagined, for helping to install long bars.
That said, if you are limited to 58" bars, you may still be able to carry the two canoes using these approaches:
1. Put both canoes on their sides, butting up against each other. This requires some clever roping.
2. Put the Explorer upside-down all the way over to one side of the bars, and lean the Dragonfly against it. (____)\ -- or try leaning the Explorer against the upside-down Dragonfly.
3. Take the seats and thwarts out of the Explorer and put the Dragonfly inside it. If this works, you may have to carry the nested canoes rightside-up.
4. Affix some 70+ inch 2x4s on top of your current crossbars. This will require some creative clamping to keep the wood affixed to the metal crossbars.