If you follow the Fox service schedule (as an example) you’ll be servicing the forks once a day and the shock once every 2 days.
I’d be sceptical about riding any suspension component for > 2500 miles with no maintenance, and if you;re plannign to have to maintain it you have to make sure you have access to seals/oil/tools/etc which rather goes against the ‘unsupported’ thing.
You coudl ride FS and have no problems but if a bearing or bush goes you could pay a high price.
I’d be lookign to do somethign of that length on a hardtail with a rigid fork but I’ve not done it (nor have any plans to) nor have I done the 1000’s of miles trainign with the setup I’d use in the race to make sur eit works for me).