Welcome. Congratulations on your baby girl!

Garters do prefer to bask (as you've seen on the hiking/biking trails), but with just a 10 gallon tank I'd be very careful with any sort of heat lamp or heat emitter. She likely doesn't need anything right now, but in the winter a mat with a thermostat would be the safest. 10 gallon tanks just heat up too quick with heat lamps... this coming from someone who practically cooked her first garter before figuring this out

You could put the heat lamp on a thermostat, too. I've done that in a pinch, but it would still be nearly impossible to get a heat gradient in 10 gallons.