I would put the base station on a new post but don't put the post in the ground. Have someone hold the post steady while you drive out and see if you're on the line. If you're off have them move it a bit. Keep doing it until you're close enough. Then stick the post in the ground in that location.

Nothing is ever perfect, even with RTK. You'll get it close enough to do a good job I'm sure. The worst thing is if you lose your AB line. Then you're not only going to be off a bit laterally, but you'll also be off a bit on the angle when you re-create the line. I think you've got it easy really.

All of this is based upon the assumption that you can still see the strips. If you can't, don't know what to tell you.