Long sleeve v necks in white for under professional wear

I am often cold in the winter in office environments or at formal affairs like weddings. I’d love a long sleeve merino baselayer to wear under my white or blue dress shirts. It would need to be:
a) white (so it doesn’t show through), and
b) V-neck so it doesn’t show at the chest/neck if the collar is open and you’re not wearing a tie.