Yes, you're right with the marriage of Costanzo ... so it stays, that it at least was used once, but very likely more often.
Generally they had Greek Mythology as a favored topic, and there were giants, for instance ...
... who in antique time probably had been a literary reflection of the coloss of Rhodos, in other words a tower with some light above to give an orientation for ships.
Atlas would give another giant picture, he appears in the later Tarocco Siciliano.
Generally it's an easy perception, that Pulci played the Guardian of some 8-12 years old boys (Lorenzo born 1449, so 12 in 1461, when "Morgante started"; Giuliano born 1461, so 8 in 1461; a cousin, who died 1463, similar old as Giuliano) and "invited friends" and that during the games Pulci occasionally played the "friendly giant", and if the boys were occupied in their own games, Pulci seated somewhere in the bushes and combined words to make a poem ... so reported by Lorenzo, I think; but at least this appears in some literature of the "boys" ... ah, here it is:
That's the famous note, written by Lorenzo in "La caccia col falcone"
http://books.google.com/books?id=iY8LAA ... &q&f=false
see: page 19
"Luigi Pulci ov' è, che non si sente?
Egli se n'andò dianzi in quel boschetto.
Che qualche fantasìa ha per la mente,
Vorrà fantasticar forse un sonetto; "
(I've in memory, that the "La caccia col falcone" is given to 1467, but that's not sure)
And if the boys took some rest, than Pulci played the poet and made some "Morgante orations", which was his second function, to get the boys involved in literature, and very naturally then Pulci was Morgante, and likely Lorenzo had been Orlando, and the other boys were naturally also heroes.
The Morgante took very quick advance towards canto 15 or 16 (I've to find the passage again, where this is reported) till 1463 ... then there's death in the family and all becomes more serious, and the Morgante stopped, evolving much later and possibly changed in some earlier parts.
And the whole text is then around 1463 an "inner-Medici-cycle-event", an amusement for the kids, and only possibly with some chances to become later "literature".
Similar the state of the Charles VI. cards ... perhaps it wasn't intended to make an edition, which left the own house, but it seems to have developed, as we hear from Florentine Trionfi cards exports. And we don't know with security, if the deck, that we have, was the original version, or an already modified version a little later, at least it seems to have bewared enough of the indications, which make it plausible to conclude, that it is "somehow from 1463".