So with the x-rite you have, you only use the grey or white point and not the other colors on the chart?
I only use the grey patch that is 200,200,200 (under the correct lighting), for "grey balance".
Those Velo WB cards may be ok. but I had some that look very similar and they are not accurate. They are cheap enough to try out though.
I really like the idea of using the photovision 14" target to get the exposure right and not blowing out the highlights too.
That is probably over the top!
I rely on using the histogram view on my DSLR; it has highlight warning too but that is a little pessimistic for raw images, ok for jpeg.
Terry