Might try sitting on the ground/bench holding a dowel or other like short handled object. Draw the legs up and place the dowel on the bottom of the feet. Slowly extend the legs out in full length (or try to) as you bend from the waist. After a few times working like this you should be able to touch the forehead to the knee area. Hold this position for a count of 30 and repeat. If there is any secret to stretching it might be to relax the opposite muscle group, as well as the area you want to focus on, while you stretch.
For extra tall people (met a lot of 6'6 + basketball players) just place the interlocked fingers at the bottom of the feet and do the same slow movement. Most normal size people can do this when they reach a better degree of flexability with this style of stretch. If having trouble with a dowel (shorter arms) than us a towel, belt, etc. This might be surprising but a lot of BBers have limited flexability in the back and shoulder girdle.
GoodMornings and SLDL's are also good ways to stretch the lower back area. With a light weight and slow reps, keep the back straight and flat while stretching. I would not suggest standing on a platform/bench, etc (looking for that extra stretch ) with any heavy weight. Try for reps and a lighter weight load. These should be just a warm-up movements. The serious stuff come in the regular DL workout.
The calf's & ham's are also important when stretching is concerned. Might try placing the toes on a 2" blosk, BB plate, etc and do GM'ing or SLDL that way (light weight). Great stretch for the chain of muscles along the rear of the body. Good Luck.
