Not sure how you would do a low temp vacuum distillation at home, but I have done the following:
Make a beer as you normally would. After fermentation is complete and and the beer is ready to drink (aged/cleared/etc.), as accurately as possible, measure the volume of your beer. Then distill it (I use a reflux still) and replace the lost volume with distilled or RO water. The taste of the now extremely low alcohol beer is very close to the original. If you don't replace the lost volume, the beer will have a cooked flavor.