Disc brake conversion for Trek 7.5 FX from 2012
New fork, wheels and brakes is a significant art of the bike. You'd be better off selling the bike a buying a new one with disc brakes. Especially as the market for cheap MTBs or hybrids is exploding in the Washington DC region during the Corona pandemic. (Yes, I looked where you located, and that's where I live too)

Going the new bike route avoids screwing around with a rear disc brake converter and ensures you have a bike available at all times. 

Alternatively, V-brakes really should be perfectly adequate and have sufficient stopping power and modulation for a road oriented hybrid. Have you considered having the brakes tuned, or perhaps upgrading the pads? Properly adjusted brakes and high end pads can make a great difference to braking performance.