If they are in good condition, I would put them in a shed with straw to eat for a couple of weeks to thin them down a bit and then put them in the freezer - hang for at least 10 days, fortnight if you can manage it.
Older weathers need a bit of a diet as they tend to lay down a lot of body fat. Even so, you will probably need to trim a lot of fat off the carcass, but it will be delicious!