The disclosed apparatus may include (1) a physical routing engine that comprises (A) a socket-intercept layer, stored in kernel space, that (I) intercepts a packet that is destined for a remote device and (II) queries, in response to intercepting the packet in kernel space, a routing daemon in user space for an MTU value of an egress interface that is to forward the packet from the network device to the remote device and (B) a tunnel driver, stored in kernel space, that fragments the packet into segments whose respective sizes each comply with the MTU value of the egress interface and (2) a physical packet forwarding engine that forwards the segments of the packet to the remote device by way of the egress interface. Various other apparatuses, systems, and methods are also disclosed.