A single 328p AVR chip can do 18 I/O pins, leaving two pins for I/O (either I2C or UART.) Even with SPI, it can do 16.
Three of those would be all you need to drive 48 analog RC servos. They only cost about $3 each.
You could even run them on the internal resonator (at 8 MHz) for low component count, and that'll give you another 2 I/O pins if you want them.
The best way to generate PWM out of a 328p is to disable interrupts, then generate all the PWMs you need in parallel in a tight loop, counting cycles rather than looking at a timer. (A fast timer is good, too, if you're lazy -- half microsecond resolution is simple to achieve that way.)
When the PWM is done for all the outputs, enable interrupts. This turns off interrupts 2 milliseconds out of every 30 milliseconds (or whatever your update rate is.)
The communications protocol from whatever controller you use will have to use acknowledgement from the receiver, as sending more than one byte to a chip that has interrupts off will drop bytes.