Preface: Do your Homework on this, it's worth the effort!
I too decided the RCS Brand of Control, but began with their EVO Throttles....the EVO's operate with a simple 2 stick radio (like an RC Car) and can trigger sound and directional lighting if you want. I recently purchased a few of the "Specials" close-outs from Tony, and dug up a few radios too...minus the Battery/Charger one can be into RC Control for less than $100...now that is pretty cost effective!
Looking over the Slope tender I have here, it appears to me that everything "might" go into the shell which would allow operation w/o a trail car. Not that a trail car is bad (how I started) but it is another option.
My boys (5 & 4) can operate the RCS TX-24 (deck card sized) remote with ease as well! It has been and continues to be a great choice for control of our trains.
I have one loco fitted with Dallee sound, an LGB switcher, it works for the kids...even if a little "rough" for me...I've not heard their steam sounds so I can't comment. I use(d) Sierra for my Steamers.
Here is a link to the EVO Page :
http://evo-rc.net/home.php
and the RCS for comparison:
http://www.rcs-rc.com/index.php
for further info you could give this guy a call, he has been Very Helpful to us! He is my RCS/EVO Rep.
Dave Goodson 425-823-3507
Good Luck, and if I can be of any help, please don't hesitate to ask!
cale