Modeling multiple low-bandwidth network interfaces on Linux

Question

I am making a test bench for a Linux-based application that uses several GPRS connections and combines their bandwidth.

I would like to test this application on local ethernet, emulating low latency network conditions at low bandwidth across multiple network interfaces.

To achieve this, I tried to configure several virtual network adapters using macvlans on the same ethernet, and then tried to configure traffic using wondershaper and netem on each interface. However, for some reason, traffic is not generated on Macvlans.

Could there be a better solution for emulating multiple cellular interfaces using a single network card?