I don't understand all of these methods. Can't just take the private key from a BCH wallet. Import into a wallet BCHSV, then import into a wallet XEC , so that we already have BCH, BCHVS and XEC, each in their wallet.
The lack of replay protection may mess it up, or insecure wallets could steal your funds. Keeping it offline and signing after receiving some dust is the safe way to go.