The smoothest tech is to have some shitbox computer (like a Raspberry Pi, I have an old rk322x Android box that runs Armbian that I got for $3 that would work like a champ for this) that handles your VPN for you. Then run your torrents on it. Then it doesn't matter if your PC sleeps, and it pulls fewer watts than your average lightbulb.
Computer sleep cycles are weird. If your system detects it, it might just not sleep when you're seeding. But it'll likely handle your torrents decently well. It's not like the tech is new, and most programs have had decades to develop specific handlers for the various sleep states.