Since you are in need of a tripod and shoot landscapes with small/wide lenses, then if I were you I would heed the following advice
This is by far the best travel tripod EVER (assuming you aren't using heavy telephoto lenses).
Sirui T-025 5-Section Carbon Fiber Tripod with C-10 Ball BSRT025
It holds solid my
K-5 + DA* 60-250 (that was just a test - I don't use a tripod with the 60-250), and folds up to the size of
a pringles can. I can confidently say that I will never buy another tripod for traveling ever again,
unless it's to replace this one with another. When hiking and/or if I am doing landscape work, I don't bring my regular tripod anymore (a Benro Travel Angel, which is ginormous in comparison) - I bring this one, and sometimes forget it's with me.
I can not recommend it enough.
The Ballhead is strong and accepts every Arcaswiss plate I've tried mounting to it. A great touch is also the included bag hook under the center (fixed - doesn't move) column so you can hang your bag under it for extra stability.
And it's only $219
After that, if I were in your shoes with your gear, I would sell the 18-55, 50-200, and the Tamron 28-300 (estimated gains would be $125-150 for the 18-55 and 50-200 combo and $275-300 for the Tamron 28-300) for roughly $400-$450 (maybe more if the 28-300 commands more? I don't know much about it). Combine that with your remaining $280 for a total of $650-750, and use that to upgrade your standard zoom to the
Sigma 17-70 f/2.8-4 Macro OS or
Tamron 17-50 f/2.8 (both $499 at B&H - I'd go with the Sigma personally) and then try and score a 55-300 on the marketplace.
New at B&H will cost you $396 currently, but used ones for the DA version are roughly $250-300 and used DA L's are about $175-200.
But without any reservations whatsoever, I implore you to very, very seriously consider that tripod, especially for your type of photography.
-Heie