Remember, in Scouting, you lead by example. Go packing yourself, and contrive to let the kids know what you are doing without pushing it. Have you been to Wood Badge? There is a lot of wisdom there. For example, you should have a lot of time during meetings and campouts to sit around messing with some intriguing bit of backpacking gear while the senior patrol leader and the patrol leaders run the show. Maybe putting lighter drawstring in a stuff sack, fitting a new windscreen on a stove, something that will serve as a lure to get a kid or two to ask a question. Be ready with an appropriate answer such as, "I'm getting my pack weight under ten pounds for my next backpacking trip. Replacing this (whatever) will save a little weight and every bit helps."
Also, remember that the whole troop might not want to backpack. That is what patrols are for - consider them to be interest groups. You don't have to take the whole troop on a backpacking trip, only the ones who are interested. Your sole purpose and roles are to bring them back alive and to be the proximate adult, not to run the show. You might extend an open invitation to any patrol what wants to go on your next trek. Remember, also, you work through the patrol leaders. They do the leading and the scoutmaster is just there - as out of the way as possible. The structure is generations-old and it works.
Living in Dallas creates a problem for adventure-minded leaders. Kids grow up on the Grand Prairie with not a hill or forest in sight. It tends to stunt their imaginations. Dallas troops regularly travel to SE Oklahoma, western Arkansas (Ouachita), southern Missouri (Ozarks), Philmont Scouting Ranch, the Pecos Wilderness of New Mexico (highly recommended), and the Wimminuche Wilderness of south central Colorado (also a great area for scouts). Local Scouters are a great source of information and advice.
Those out-of-state destinations are a long way from home. Scout leaders in the Dallas area may have developed some nearby opportunities that could work for training trips, but to really give the kids the bug, you will have to go somewhere inspiring. That's unfortunate, but just the way it is. I grew up near there, so I speak from experience.
An alternative is river tripping. The Brazos and other rivers in the Dallas area provide good opportunities for treks of several days. (Be aware of the safety concerns with river trips.) It isn't backpacking, but you have to work with what you've got.