Go w/o a board!
BTW, eyeglass prescription is somewhere in the vicinity of -5 diopters
Test to simulate my myopia.
1) Tripod, AF through live-view on bag, take shot using timer
2) Hold pair of eyeglasses right in front of lens, force camera to AF through glasses until focus lock achieved
3) Carefully switch to MF mode w/o disturbing anything
4) Shoot again