Forcing a tab stop on a hidden element? Possible?

Keep the radio input hidden, but set tabindex="0" on the <label> element of reach radio input.

(A tab index of 0 keeps the element in tab flow with other elements with an unspecified tab index which are still tabbable.)

a working solution in my case to enable tab selection / arrow navigation was to set the opacity to zero rather than a "display: none"

.styled-selection input {
    opacity: 0;         // hide it visually
    z-index: -1;        // avoid unintended clicks
    position: absolute; // don't affect other elements positioning
}