Well, you can go around from the south through Hondo and then via Utopia which will take you straight into Garner.
I did some riding in Leaky last weekend and we drove back home that way. This is all very flat and the vast majority was free of traffic on Sun morning.
The route from Vanderpool to Leaky is hellishly steep and difficult. If you are carrying weight, it will suck big time.
You might also look for a route from SA -> Bandera and then Utopia is easy from there.