Design a simple circuit with 2 x WS2811 LED drivers, but for higher ampage outputs

This project is to create a design and working prototype for a circuit board which uses 2 x WS2811 MSOP8 chips to control 6 x external 5V DC devices. The external devices might be relays, lasers, LEDs - anything which requires 5V DC to operate. The board will also have 2 x SK6805 LEDs, and connections for a diode. It will ultimately be controlled via a device (Arduino, RPi) capable of controlling WS281x RGB LEDs. The WS2811 is only capable of sinking 18mA per output, and I would like to be able to control devices which require more than 18mA (up to 500mA per output if possible) - also note the WS2811 outputs are low when activated (100% PWM), and high when deactivated (0% PWM), and I would like this reversed for the outputs so that there is 0V at 0% PWM, and 5V at 100% PWM. This board will be placed inline with other WS2812 LED strips, so the power tracks need to be similar in amps capacity to standard WS2812 LED strips. PCB size and component cost is going to be very important. The circuit should have 3 inputs at one end of the board (5V, Ground, WS2811 Data In) and 3 outputs at the other end (5V passthrough, Ground, WS2811 Data Out) via 2.54 pitch headers, similar to the images attached. The 6 outputs may have 2 pin phoenix screw terminals connected, so enough space should be left for those. No screw terminal connectors are required for the prototype. I require a working circuit design, BOM, and PCB layout / Gerber files - plus a working prototype board before all monies are released. I can provide some of the components for prototyping (WS2811 SOP8, WS2811 MSOP8, SK6805 LEDs etc). I can also provide a semi-working board and design from a previous attempt at this project for comparison - however there were issues with that board - the RGB LEDs work, but : 1. When affecting the WS2812 outputs, the SK6805 LEDs flash - they should not. 2. The WS2812 outputs do not go from 0V to 5V as they should, they always have voltage. 3. The ground connections are not common, 5V is instead. 4. There is not quite enough room for screw terminals on the outputs When the design is done and full design files and gerber files released, I will release 1 milestone payment, to cover the cost of ordering the prototype - from pcbway, or other pcb prototype manufacturer. Only when a manufactured prototype board is shown to be working will I release the rest of the payment. If the prototype fails to work, I will not be responsible for paying for more than 1 prototype, so having the design working on a breadboard first is preferred. The cost of the prototype creation must be included in the cost of the project.