Originally Posted by
Manfred M
Get the best tripod you can afford without a centre post. Weight is not really an issue as most decent tripods have a hook that you can use to hang weight on to stabilize it; that will take your total weight up. If I have 15lbs of camera gear, I will easily hang 15 - 20lbs of weight to keep the tripod steady, so your base load can go from the 15 lbs you are thinking of to 30 - 40 lbs quite quickly.
If using it on soft ground (grass, dirt, etc.) look at something that also comes with spikes rather than the more usual pads on the bottom of the legs.
Frankly stainless steel is not going to be a great material for tripods and I am not aware of any made from SS tubes. As you are not going very far, aluminum should be fine (and inexpensive) as materials go. Tripod ratings are rather "iffy", when you look at the rated weight.
If you are looking at a maximum of 15 lbs of gear, I would not get one rated at less than 30+ lbs (more is better) and get something with as few sections as possible (I would suggest 3 maximum) with as large diameter legs as you can find. Don't forget that your head needs to be rated for roughly the same load as the tripod (a tiny bit less, as the head's weight can be left out of the calculation).
The main issue is your price range. Heavy duty tripods tend to be more expensive.