Other than the construction zone east of Leakey, the rest of 337 to Vanderpool is an awesome ride. Ride out to the construction from Vanderpool, then turn around. It's only about 20 miles out and back.
Alternative routes between Vanderpool and Leakey exist.
One would be 187 south to Utopia, west on 1050 to Garner State Park, then north on 83 to Leakey. This route is 20 miles longer than 337.
Another alternative would be 187 north past Lost Maples State Park to 39, west on 39 to 83, and south to Leakey. This route is about 22 miles longer than 337.
If looking for a faster route direct to Leakey, 470 from Bandura to Utopia and 1050 is only a 7 miles longer than 16 to 337 in Medina. From Kerrville, take 27 to Ingram, where you pick up 39 to 83, then south to Leakey. this route is only a mile or so longer than taking 16 to Medina to pick up 337.