I don't know if there are a ton of uav people on this forum, but I also don't know of a better place to ask this question either. We have been operating the X-UAV Talon for a couple years now and are pretty pleased with it's capabilities. It is relatively efficient, inexpensive, well engineered, has a big payload area, is pretty easy to hand launch, and can belly in to a lot of semi-rough places. We do aerial surveys so we aren't going long distances away from us, but we do cover a lot of ground within line of site. Our camera payload is about 500g (sony a6000 mirrorless camera) and we can comfortably achieve 1+ hour flight times on a 8000mah 4 cell battery. Our longest flight so far is 77 minutes on that amount of battery. Battery life depends on how aggressively you run the throttle which depends on your target cruise speed. 25-30 kts (maybe 12-15 mps) is a pretty comfortable easy cruise speed for this airplane at < 1/2 throttle.
There are many ways you could do this and many other aircraft available that might work out ok ... I'm not here to tell you what's best, just hopefully to get you thinking about the different important factors to consider.
There are also many ways to engineer (verb). I would recommend you start smaller and work your way up. You'll need someone that is a fairly competent RC pilot (or you will need to gain these skills yourself.) Like any other skill, it's just a lot of practice and patience to gain the experience. You'll also need to gain experience with the ardupilot (or px4) if that's what you choose to use. Some of the learning curves you will encounter will be pretty steep. There is no end to the unexpected mistakes we all can make that will crash the plane. Some things are just obvious to people that have been doing RC for 30 years and we don't even think twice about them, but they can be completely non-obvious to a person setting up a plane for the first time.
For example: CG (center of gravity, or where the airplane balances) is critical to have correct or the airplane won't fly well or at all.
Workmanship matters (imagine a sloppily folded paper airplane competing against a very carefully and precisely folded paper airplane ... even with identical paper and identical design ... which would you put your money on?)
For UAV's especially, quality components matter. A failed servo or receiver can quickly crash your airplane. A typical hobby plane might do a few (or a few dozen) flights a year where each flight is 5-10 minutes. There are exceptions -- some people fly a lot -- but I bet for most people and most of their aircraft, if you added up total flight time over a year (in minutes) it wouldn't be very much. Compare that to a production UAV -- if you are doing multiple deliveries per day, you could be racking up hours and hours every week. Also the consequence of a servo failure in a light foamboard airplane in your back yard is much different than a UAV doing real work and your business and reputation depending on it.
Prepare for crashes. People don't like to talk publicly about their mistakes and failures, but the attrition rate of fixed wing UAV's is typically very high. You should plan to be building up the replacement before you even get the original in the air for the first time. You might go through a 1/2 dozen airplanes before you get close to accomplishing something like your original plan.
From a business standpoint, don't forget about weather. Consider what weather conditions you need to safely fly and how often the winds in your area might exceed safe limits ... or how often it rains, or how much of the day is shut down to a thunderstom threat, etc. I live at a fairly northern latitude where we can literally go weeks at a time during the winter with no flyable days.
So my recommendation is to start small and inexpensive and build up slowly towards your ideal system as you learn and have successes. There is a lot to learn and a lot to consider beyond the basics for RC flying. But it also can be a lot of fun and extremely satisfying to achieve a successful "production" flight. There will be setbacks along the way that will feel like you got sent back to the starting point with nothing to show for it. Just be patient and have a long term focus.