tyler - The Tioga 4 will work fine for a 5wt, especially if you use a WF5 line. Here is the info from my Tioga owners manual:
Tioga 4, 4.6 oz, WF4F, 2.95" dia, 100yd 20# backing
Tioga 6, 5 oz, WF6F, 3.2" dia, 150yd 20# backing
You should get around 75 yds of backing on the Tioga 4 with a WF-5-F line on it, and it will look fine. I've used both sizes on a 5wt and prefer the Tioga 4. Or you could go with the Tioga 6LA (about the same amount of backing as the Tioga 4, more weight) - depends on what balances on your rod better - 4.6 oz versus 5.5 oz(LA6). The Tioga 4 will give you the option of using it on your 3wt with something like 125 yds of backing. Hope I've helped you rather than confused you!.........Ed