Three bikes and twelve tie-downs? WOW! I must way you secure things a little better than I do. :eek:
Try this simple fix, turn the middle bike around backwards and tie down. If you don't have a tail gate on the trailer, just cut, bend and weld a piece of C4 x 5.4 iron channel to 120 deg. (+/-, depending on your preference) for the front tire to sit in. Bolt down the tire channel and you're good to go. Don't forget to put a plug in your silencer in case of rain. :scream:
In fact, if you live anywhere close to me, I have a couple spare bent channels alying around.....