Not sure what you meant by external income, but if it is good for 8 years, and you'll be debt free in 2, then the other six could go toward saving what you'd been using to get debt free.
I think the best bet is to make sure you do as much for yourself as you can, then don't have to pay for those products or services. Garden, do as many repairs as you can yourself, make less trips to town or wherever...shop only what you need maybe once a month, and buy in bulk. Maybe you can also barter some things with neighbors/friends/relatives, so if someone raises their own meat, you could barter veggies or fruits for some meat. whatever you don't pay out means you need less coming in.