You need a pruning/training plan. Start be cutting back to the base next spring. Yes cut off everything. Then train the strongest shoot up a stack to form the future trunk of your vine. Pinch the tip out when the new shoot reaches the trellis wires. Train a shoot in each direction on the trellis. From there decide on cane or spur pruning and proceed accordingly.

You won't lose any growth by cutting back hard next spring. At this point it's the size of the root system that counts not top size. The first yr is to grow roots. Year two is to start forming the vine.

Thanks. The root growth this year is exactly what I was concerned with so did nothing. I am quite hopeful that the vine will do well as it survived a very nasty late freeze this spring that killed many mature shrubs and trees in the area.

I was planning to have wire on only the tall ( 5' or so) horizontal plane and have 2-4 wires there. Can the vine be trained to 2-3 major trunks with two arms off each? Or should I train one trunk front to back and run arms off it at each wire? If it takes more time, that is OK.

Multiple trunks is fine and maybe better if freeze injury is common. Grapes are very forgiving of different pruning and training systems. As long as the best wood is left each yr for fruiting it doesn't make a lot of difference. Some varieties are better spur pruned than others. I've grown dozens of varieties cane pruned and all worked well.

It's also easy to change training system in mid stream. Multiple trunks to single or single to multiple. Cane to spur or some of both on the same vine. It mostly all works. You can keep all six of the current canes as multiple trunks and that will work as well.

Once you understand how to remove as much old wood as possible each spring while retaining the best fruiting wood you've got it made. Maybe you understand that already. Mainly I'm talking to the others that will read this.

Assume I know practically nothing. There are some helpful youtube videos.

Thanks again.