I have been bottling for almost 3 years, and I have recently embraced the need for perfectly clean bottles. Personally, I like a hot soak in PBW for 30 minutes or so, before rinsing and spraying with Star-san. The problem was that it was always a bear to get the bottles filled with PBW.
Here is what I came up with - maybe it will save someone else some time.
First, I fill my bottling bucket with ~5 gallons of PBW solution, and allow my auto-siphon, tubing, bottle filler, etc., to soak. After 30 minutes, I put the bottling bucket on my kitchen counter, and keep 2 cases of bottles at arm's length. Below the bottling bucket, I set up 2 homer buckets, both filled about 1/3 with PBW solution. I then simply open the spigot of the bottling bucket, fill a bottle with PBW, and drop it into the homer bucket. As the homer buckets fill, the bottles displace the PBW, and the liquid level raises to the top. If you work quickly, you don't even need to keep opening and closing the valve on your bottling bucket, and the 5 Gallons of PBW will be enough to fill all 48 bottles. Also, the 2 homer buckets are almost the perfect size for holding 48 bottles (the last couple stick out the top).
After the bottles soak, I create a bit of a 1 man assembly line, where I rotate a bottle being purged of PBW (inverted), a bottle being rinsed with hot water (you can just leave it sitting in the sink under the running faucet) and a bottle drip drying on a paper towel on its way back into the case.