Advice on Grill/Smoker Design

[SmokinGumby]

I have a natural gas well on my property, so I've been wanting to build a permanent brick grill/smoker for years. Now that I'm getting more into smoking, I'm wanting to pull the trigger on getting it done. I want to keep it very simple and inexpensive, so I was thinking of doing something very simple.
My primary question is how I can make one vertical unit both a grill and smoker.
I had 3 thoughts...
The first is that I could put a burner in the bottom and grill down at the bottom and smoke up in the top. That would be simple to build, but then I have to grill bent over and squatting, which is certainly not ideal lol
My second thought was to make the burner adjustable, so I can move it from the top to the bottom. That would surely work, but would be a complicated build.
My third thought is to set the burner a little low, but high enough to grill, and have a removable tray with lava rocks that I could put over the burner but under the grill rack and put wood chips on it for smoke. This seems like the easiest/best plan, but would the tray with lava rocks create a diffuse enough heat to cook indirectly? Or should I make it extra wide with space that isn't over the burner, like charcoal all to one side?

 

[daveomak]

Be sure you have a "Flame Out" protection device on any burner you install....

Man killed when meat smoker explodes
Colleen Kottke, The (Fond du Lac, Wis.) Reporter 4:49 p.m. EST December 15, 2014

(Photo: The (Fond du Lac, Wis.) Reporter)
TOWN of LAMARTINE, Wis. — A Wisconsin man using a homemade meat smoker to cook turkeys and chickens died when the smoker exploded, police said.
Richard L. Zabel, 55, was found dead Saturday afternoon inside a machine shed.
"The North Fond du Lac Ambulance and Lamartine first responders were called to the scene for the initial report that someone had fallen," said Lt. Cameron McGee of the Fond du Lac County Sheriff's Office. "When investigators arrived on scene, they discovered that a 55-year-old man was dead inside the building."
Zabel, a town of Lamartine man, did not live at the building's location, but lived nearby.
"Evidence indicates that the flame on the LP burner went out and as a result the gas continued to accumulate inside the smoker," McGee said. "And when (Zabel) went to relight the burner, the spark from the lighter caused the gas to explode."
McGee said the force of the explosion caused the heavy duty door of the smoker to blow open, striking Zabel in the head, killing him instantly.
"When something explodes, it's going to blow open at the weakest point which was the door, which was triple-latched," McGee said.
McGee said the smoker was larger and better constructed than most store-bought models.
"It was about 4-feet tall and about 3-feet wide and built really solid, including the door. Someone really put a lot of thought into building this thing," McGee said. "We were told that they had been using it for the past three years without any problems."
The Fond du Lac County Sheriff's Office is investigating the incident.