Right, so the solution is to make do with 1080 and all is good, 2K is only slightly bigger than 1080, right?
So is there an option to down it to 2k for 60fps in settings?
2K has 2x the number of pixels as 1080, 4K has 2x the number of pixels as 2K (4x 1080).
So you get twice the detail in 2K compared to 1080, and four times the detail in 4K.
To convert from 4K to 1080 is easy, you just combine every 2x2 block of pixels (4 pixels) into 1, and you get a perfect result, with one quarter the detail, which is a big loss just to get twice the frame rate, when you probably don't need the extra frames.
To convert 4K into 2K you just drop 1 out of every 3 columns of pixels and 1 out of every 3 rows of pixels, another easy conversion to do, and you end up with half the detail, which can still be a significant loss but not nearly as bad as losing three quarters of the detail. There is a side effect that diagonal lines become a bit jagged, but that is not too bad for evidence purposes.
Most people seem pretty happy with the conversion from 4K to 2K, watching on a 4K TV screen many people don't have good enough eyes to see the difference, but there is a loss of detail. It is not just Vantrue that can do it, Viofo also do it on their 4K camera, but the Viofo camera can record in much higher bitrate so records more information, so the loss of detail is more noticable. If you are using a low bitrate 4K camera, such as Blackvue then you quite likely won't notice the difference even if you have good eyes and a big screen!
My recommendation is to stick to 30 fps if your video is for use as evidence, you very rarely catch things at 60fps that are not also caught at 30fps when you have 4K. With 1080, because the resolution is a quarter, you can't see nearly as far, so there is far less chance of catching things. If you record in 1080 from a 4K sensor, you are roughly halving the distance at which you can see a plate, halving the number of frames that record the plate, so canceling out the increase to 60fps, while also more than doubling the amount of motion blur, which is often what actually stops you reading a plate in 1080 resolution!