Mash times/temps don't really matter if you add gluco..you'll get a dry beer no matter what. i do a three step mash though because i use home malted barley. I heat my strike water to ~132f, dump ~20#'s malted barley in my kettle, put the lid on and let it sit at ~125f for a protein rest for 20-30 min (otherwise i get plant milk), then i turn on the burner and bring that up to 150-155 with constant stiring, then transfer from the kettle to my 10gal round cooler, let it sit for ~30 min, then ramp up the temp to 162f for a alpha amylase rest (because of home malt again, i have to too get my 85% efficiency. otherwise i just get 75%)..let it sit at 162 for about another 30 min, sparge for an hour or so...
But that's brewing the hard way! if you add gluco to any beer it's going to be virtually 0 carb! just add it with the yeast to the fermenter...it will finish at 1.000, and as long as you have some dark/crystal malt in the grain bill it will still have plenty of body.
The hipsters even coined the term 'Brüt' for it!
And at 72 years young, you've out lived both my parents already! hopefully you'll be like my friends gramma alive and kicking at 97 years!
here's a link for what you need to make low cal/carb beer:
https://brewhaus.com/gluco-amylase-enzyme-amyloglucosidase-2oz/
just like 5g's for a 5 gal batch will do the trick...