peep
Trying to run a peep sight in reduced light is just plain tough...period. There was a time when I hunted peeps a bit, and using them in the fading light of dusk, was a real problem. So much so, that even when my eyes were much younger, I abandoned peeps for PM hunts as they robbed me of 10 minutes or more of shooting time in the evenings. The best peep set ups I've used in bad light have been the XS type,with their big ghost ring and white highlighted front blade. Even then, they don't gain you much once the light fades.
I note that you do not want to modify your Garand, I don't blame you. But one thing you might try is obtaining a GI aperature and opening it up some to form a ghost ring rear, and installing the modified aperature in your Garand. Appearance wise, it will be hard to note the enlarged opening. With some paint out on the front blade, one might gain a few minutes of shooting time....but it won't be much. If the experiment doesn't work, you can reinstall the standard/unmodified aperature. You won't loose any accuracy at typical hunting ranges with the ghost ring, but it might show up at longer ranges on paper. You will have to weigh the lost opportunities in bad light, against the desire you have to hunt w/ your Garand in the late PM.
BTW, I applaud you hunting the Garand. My solution to do same was to install a rail (an Amega, but Ultimak is good too) and an IER scope. Before settling on a 2-7x IER, I ran a small red dot, which worked pretty good too, but the scope allows for more precision at long range and target descrimination. The Amega will allow other mount options if one desires (like a light or laser). That is travesty to all purists, but a viable option when hunting with the peep is no longer an option.