I always love a good theoretical challenge when talking about wines. I have never made a super high ABV wine (20%+). But I have read a few articles/forums about Brandy and making it from Welch's Concord grape concentrate.
For what I have read up on you do need to take super good care of your yeast to try and keep the fusel oils down and rocket fule tastes. I would probably step feed sugar and concentrate with your turbo yeast to help it get to high levels. Plenty of O2 would be required as well. A recipe may start like:
1 gallon (but brewed in a 2 gallon bucket)
Start off day one
2 cans of Welche's red grape frozen concentrate
1 tbs of black tea (earl grey or another favorite)
1 tsp yeast nutrient (dap)
1/2 tsp yeast energizer (something like fermaid O)
Water to one gallon
Yeast
Day two add:
1/4 tsp yeast nutrient
1/8 tsp yeast energizer
Day 3 add:
1 can of concentrate
1lb of sugar
Day 4 add:
1/4 tsp yeast nutrient
1/8 tsp yeast energizer
Day 5 add:
1/4 tsp yeast nutrient
1/8 tsp yeast energizer
Day 6 add:
1 can of concentrate
1lb of sugar
Day 7 add:
1/4 tsp yeast nutrient
1/8 tsp yeast energizer
Day 8 add:
1/4 tsp yeast nutrient
1/8 tsp yeast energizer
Day 9 add:
1 can of concentrate
1lb of sugar
Day 10 add:
1/4 tsp yeast nutrient
1/8 tsp yeast energizer
Day 11 add:
1/4 tsp yeast nutrient
1/8 tsp yeast energizer
Day 12 add:
1 can of concentrate
1lb of sugar
After day 12 let it ride. also check original gravities and record gravities after adding sugars so you can track how many points drop. That should be enough sugars to get it close to 23% - 25% ABV if taken dry. Also 2 - 3 times a day through the 12 day process hit the must with a wine whip or air bubbler for a couple minutes. Should be interesting if you can get it that high. Once you rack to secondary adding 1/2oz of dark toasted ok for a couple weeks should help.