Setting a limitation on the number of cards to display would certainly help, both from an XML and scripting point of view. And keeping the game to just a single PC versus a computer AI would also help.
As I say above, the hardest part is (in my opinion) would be to write the script code to handle the cards themselves and the randomisation/tracking of the “deck” involved. For example, in a regular 52 deck, you have four suits, or more importantly, four types of each card. E.g Four lots of 3’s etc.
i.e. You are not limited to only ten cards (from an XML point of view), but are dictated by the size of the deck you are playing with.
So, when the player draws (or is dealt) a three, you need to track that that particular card (3) is used from those that may be randomly delivered from again. However, If you further restrict your deck in some way, then the coding gets a little simpler.
It can be done with any number of cards/displays, but, as you can imagine, the coding become more complex.
As a (virtual) template, try to imagine a deck of cards, and how you would manage all the cards in that deck between the two players (PC v AI). If you can construct your game in such a way that uses a smaller deck, then it may be easier to manage. The thing about games like Blackjack, however, is that they have more than one possibility of the same “numbered” card turning up, and so removing that (to make things simpler) may also end up compromising the experience you are trying to achieve.
Personally, I would probably look at designing a completely different game to allow easier coding and a different experience to what is already available. Sometimes the simpler stuff can be just as fun without the potential headache.
That all said, if I ever get to the point where I have time to spare, I imagine it to be one of those challenges that may be fun to write as an add-on for builders like yourself to include. I remember writing a very simple dice game for a friend in NWN1 once, which he enjoyed using.
These would certainly save some time for the images, but do not help with the actual scripting time.