If you can't find any sailing gloves big enough, check the internet for golf gloves, motocross gloves, crosscountry bicycling gloves, rugby gloves. You might find something that fits you and that also works as well as or better than a made-for-sailing glove.
Also, somebody makes gloves that are stretchy. A friend gave me a pair of gloves once that I thought were so small I could not possibly wear them, but they stretched to fit, had a leather palm, and were the most comfortable glove I have ever had for sailing. Probably not very durable, but they also were not very expensive. Sorry, I don't know the source. They might have been golf gloves.
