You can put money on your account when you check in I believe. If not then I know you can once on board at guess services. You can pay your tips anytime once on board as well. Your Shore excursions are not billed untill you have completed them just in case they need to be cancled due to the weather or any unforseen reason. A guest changing their mind does not count.
I have read about people who have set up prepaid accounts but do not know how to do this. I always leave what little extra I have in my checking account and use my charge card while on vacation. Then I pay it off when I return. My bill is a good way of tracking what I spend and I can double check it against my
DCL bill. I do not need to worry about losing the cash. I do bring ones for tips and money for laundry.
You can call your TA if you are using one or call DCL and ask. I am sure if this is important you can find a way to make it work.