I did this in a much smaller way last year. When I was safely out of my size 26's I posted a thread on here that I would donate them to the first person to respond that needed them as long as they agreed to do the same with the ones they had. I am not sure how many people actually did it but it can be kinda neat. especially in the plus sizes since it is harder to find bargain stuff in these sizes
I have been donating mine to the thrift store. It's nice to know that there are some larger sized clothes for someone who needs them to find them there.
Most of mine went towards goodwill ^_^...The clothes I have now will go towards my sister when they get to big, as shes trying to actively lose weight now too and will need next size down clothes