[BrianG]

That might work although I would still opt to use a UBEC. The one in the Rx is probably just a linear regulator and will heat up substantially, especially when using high cell counts and/or heavy duty servo(s). Besides, it does not say what the current rating of the BEC is or the max allowed cell count. A UBEC uses a PWM regulator so it is much more efficient and heats up a LOT less.