Someone else already uploaded a mod, I think 1 or 2 weeks ago, which did exactly that, however the way rocket silo requests and item stack limitations work with their cargo, changing payload capacity does more harm than good, and I suspect because of that the mod author deleted that mod (and I stopped using it as well).
For example, if you were to increase the payload capacity to 10T, you'd still only be able to send up only 100 red belts, but other items which are not limited by quantity, but weight, will need a LOT more items to complete a request. At 1T the advanced circuit limit/rocket are 5 stacks, or 1000 units. At 10T, that would be 10x as much, and the rocket wouldn't launch until 10000 red circuits are in its cargo, which would result in the rocket never launching because it doesn't have the inventory slots to accomodate all items. Or if it does, depending on your production rate it might take forever to fill up a cargo.
As for individually modifying each item, I'm not much of a programmer, but if I had to guess there's probably a way to do it without editing each item manually
