Amex for one starts the 180 day countdown at the day of delivery or expected delivery, so you can get them to reverse a transaction literally years after the fact if necessary -- pre-ordering Duke Nukem Forever in 2005 would still be chargebackable into 2013. They're also well-known for bending over backward for cardholders, particularly very valuable cardholders. (They require merchants to retain all records for 24 months. You can probably get them to reverse transactions after that, too, though it's an open question whether they'd eat it or have the merchant eat it at that point. For high-value customers they can be quite accommodating indeed.)
There are also fun edge cases with foreign banks, corporate/government cards, etc etc. Paypal says they (very rarely) get chargebacks 540 days out.
With crowdfunding the date of delivery is the date the campaign completes, not the date the rewards, if any, are shipped/published/whatever. At worst given the typical 30 day campaign that means they don't need to worry about chargebacks more than 220 days out. That's still nearly a year, but honestly I think once a campaign funds they shouldn't even process chargebacks against it unless the original backing can be shown to be fraudulent (I.E. stolen CC).
It seems that way to me too. Funding a campaign isn't buying a product (and that we have coming to treat it as such is a Problem). The question, I suppose, is whether the credit card company will see it that way.
Years ago, when I was working on a shareware app for the Mac (long before the App Store), I released the beta as donationware, and gave users the incentive of a free license for version 1.0 if they donated a certain amount (which increased with each update). It was very small scale, but it allowed me to bring in some income while I was working on the project, and gave me an incentive to get it done. But it was an incentive for a donation, and that donation could be any amount. It wasn't a preorder, and it would have been silly to treat it as such.
It actually hadn't occurred to me until just now that what I was doing was crowdfunding before it was called "crowdfunding".
There are also fun edge cases with foreign banks, corporate/government cards, etc etc. Paypal says they (very rarely) get chargebacks 540 days out.