Craft a bow that applies Soul Trap if the target dies within 1 second. That's all you really need, and you can use it for a very long time with the 1 second rule. Why 1 second? Because you aren't going to really be doing damage over time with a bow. You will usually be 1 shotting enemies to begin with.
This is exactly what I did. Realized that mob was dying quickly so I cranked down the duration of the soul svck to increase the number of charges. Much better way to do it, dont need nearly as many SGs. Also, I am well geared for the most part, having made much of my own gear, I carry 2 swords. My main sword is unenchanted, just well crafted. It never runs out of a charge.=P And for the big tough fights I have the same wep with chants on it to boost dps when needed.
And since the SGs weigh half a pound each!!!!, alot of my carryweight issues went away!