Finally got a chance to run this today. Had a blast! My players will always remember the heroic sacrifice of Viney Vinnsauce.
Some mechanics I came up with on the fly included using an oversized MtG spindown to roll with advantage on a sneak attack, repeated checks to climb the walls costing HP for the next encounter, introducing an ally NPC for one fight (I wanted to try rolling too), and for the final encounter as the sun rose, I did a wave-based encounter where each enemy killed before sunrise would restore 1 HP and progress the time, and once four were killed, I summoned a Patriarch, with the dawn initiating as a fifth was brought to 1 block left (remaining alive due to the Patriarch), dealing 1 damage to each enemy at the start of a round.
One thing I've found is that the Spine Gourd is surprisingly strong. Being able to guarantee damage against a 1 block enemy is not to be taken lightly, as the last hit point is otherwise the hardest to take.