I've done some long distances including a few double centuries. However I'll address the gout as I know that subject all too well.
1. Don't get dehydrated. Drink more that you think you need both off and on the bike but especially on the bike when hot.
2. Would you happen to be on any blood pressure medications? Something like Lasix or diuretics can lead to gout attacks. I found this out the hard way.
3. Drink less alcohol. I love my beer, but hate gout more.
4. Watch out for certain foods such as shellfish. You can find lists of what to avoid with a google search.