need ideas for propane connections for 3 tier gravity system

I'm almost done with my set up. 3 sanke kegs with welded in couplers, Blichmann brewmometers, sight glasses. Looks good! I bought a nice welded industrial style rack with plenty of capacity and put some nice casters on it. I cut to size some heavier duty metal shelving for the burner grates which should hold up nicely. I have 3 BG-10 Bayou classic burners and need advice on hooking them up.

My questions:
I want to use 2 propane tanks. the first to split off to the HLT and M/T. The second will be dedicated to the BK. Can you use flexible gas line since I would like to be able to move the burner up and down as needed which is nutted on an adjustable bar underneath the grill. what is the optimal height under the 15.5 sanke keg for the BG-10. I do have 2 seperate shut off valves for each line. Is copper good or brass?
Any body have some pix or ideas or problems they experienced?

These might help you, not sure how much range of movement you are looking for. Dave

http://www.plumbingsupply.com/gasconnectors.html

not sure myself. I'm just trying to find that balance between being to close to the keggles and finding just that right heat distribution to control the temperatures. I figured I would need something that was flexible so I can adjust it. I would take a hard line up the post and then split it.

From the research I did on here, it would seem that most people are running those burners between 4" and 5". The stand I have been working on I put the burners at 4 1/2" but I built in some adjustability.

Here is a link for some decent priced propane connectors, etc, that I just found on another thread today:

http://www.agrisupply.com/category.asp_Q_ipp_E_0499_A_t_E_c_A_sb_E_0_A_action_E_showall_A_c_E_5400001

I don't know if this would work for you but they have a 3' long "Lp Gas Hose Assembly" available.

You could set it up much like you do for the TopTier. Use iron pipe as a manifold and then just a short length of flexible gas tubing.