The solution is not that hard. Other Democratic countries have solved this problem decades ago. Puhlease. In my native country, Costa Rica, EVERY citizen has a National ID card called a CEDULA. EVERY CITIZEN.
There. Problem solved. No matter where you live, you can vote, even in extremely rural, mountainous areas!!! Just keep your "cedula" current with your current residency, which should be made easy to do. And the "cedula" should be FREE!!!
I'm 1000000% sure Republicans would be 10000000% AGAINST this idea though. Wonder why!