If your planter is mounted on a toolbar, you can mount it offset to one side behind your tractor. In other words, "pretend" you have a two-row planter by marking your toolbar where you'd mount two planters if you had them. Then mount your one-row planter on one of the marks and leave the other mark empty.
During your first planting run, the planter will plant one half of your "pretend" two-row planter. At the end of your first planting run, turn around and go back in the exact same tire tracks -- your one-row planter will now plant the other half of your "pretend" two-row planter. The results will be exactly the same as if you had used a 2-row planter -- the only difference will be that you've had to make two passes to do it.
If your rear tires are 18" wide with outside edges at 84", then the centerlines of your rear tires are 66 inches apart (84-18). You can have perfectly evenly spaced rows 33 inches apart with that setup. If you had a 2-row planter, you'd set up each planter to be 33/2 = 16.5 inches to the left or right of the tractor centerline (also works out to be 16.5 inches inside of the left and right rear tire centerline). For the one-row planter, of course, pick a side and mount it on the 16.5 inch mark.
Plant your first row, then turn around and return in the same tracks for the second row, as I described above. You'll now have two rows spaced 33 inches apart. For the third row, keep one rear tire in exactly the same track you've already created, with the other rear tire in fresh dirt (not yet planted). You'll be planting that third row exactly 33 inches from an existing row (your rows will always be exactly 16.5 inches from rear tire centerlines and 16.5 inches from the tractor centerline).
Just a suggestion from a fellow one-row planter owner.
Parker