But that assumes that the requirements can be given correctly. And that there will not be changes needed in the future.
And finding someone that will do it right with the equipment that already exists will probably not be cheap. The RB3011 uses two QCA8337 switch chips that don't have support for HW offloading when using the "modern" vlan-filtered bridge, so to be able to extend the vlans between the Cisco SG200 and the RB3011 will require the more complex vlan setup using the /interface/ethernet/switch method instead of vlan-filtering bridge if you want to have the vlan processing done by the switch chip at wire-speed instead of using the CPU (which consumes processing from the CPU and is also slower). This is only needed if you want to be able to use ports on the RB3011 as switch-ports.
If you want to be able to support it, you will need to understand it. You could hire someone, but unless you work with them, you will have to keep going back to the well when something changes. From your initial post, it sounds like this is something you are doing as favor/hobby, and not for a business, where spending the money for a professional setup would probably make more sense.
The easier to configure and if the SG200 has sufficient ports for all devices, would be to let the SG200 do all the L2 switching, and have the RB3011 be only for routing.
See the following thread for more information about vlans on the RB3011
VLAN performance issues in routing on RB3011
RB3011, VLAN switching/routing and DHCP server
The above threads also have links to other related material.
Also see the RB3011 block diagram
