My DW and I went to HDDR in May and we took the bus. There was a bus that left directly from WL and took a service road over to FW. We got there in less than 5 mins. This particular bus is designated for the HDDR. Buses to other parks take a different route to FW first, then to the parks.
You could take either bus or boat. The walk from the boat dock looked a little longer than the walk from the bus stop to me. I mention that only because we did HDDR after a long day at the parks. (Sore feet, you know!)