Thanks for the tool, just some additional information if anyone is interested.
I was a bit concerned about the mining fee, as here a warning is stated:
Warning: if you don't pay at least the fee rate specified, then BitPay might not register your payment. Round your fees up if necessary.
However, it works fine with lower fees, BitPay will just send you the following e-mail and confirm your transaction when it was accepted:
What's going on?
Your bitcoin transaction has been broadcast, but it does not yet have any confirmations. BitPay does not have your money. We also cannot control when transactions are confirmed on the Bitcoin network.
Why is this taking so long?
You created your transaction with a low bitcoin miner fee, which goes to pay the Bitcoin network's cost for confirming your payment. This low fee may prevent your payment from being confirmed on the Bitcoin network in the usual period of a few minutes to a few hours.
What now?
If the transaction confirms, the funds will be credited to the merchant and you can receive your order or request a refund from the merchant.
If the transaction doesn't confirm, the funds will be spendable again in your wallet. Depending on the wallet, this may take 48-72 hours.
How do I prevent this?
If you want your transactions to confirm faster, use a true bitcoin wallet (instead of online exchanges or accounts) that will automatically use sufficient transaction fees.
BitPay Wallet users can update their transaction fees to Priority in their wallet network fee policy settings.