Yes, you can build a tunnel between two FusionHub VMs without a problem, however the FH is mostly intended as a VPN concentrator so its capabilities are somewhat limited compared to a Balance appliance… oh if only Peplink would offer a Balance VM 
You can however though route traffic out of the hub towards another router on your network, I’d probably add a second interface to the FH for this and then depending on your needs turn up OSPF or BGP to the FH or just a couple of static routes I suppose if your network is simple enough.
With regards to performance I think for that sort of throughput you probably want to consult with Peplink directly as their guidance sheets only really go as far as what they would recommend for 1Gbps of traffic on the FH and on the hardware side they really only make the EPX that can even get close to that level of throughput on paper.
We run ours FHs modern Xeon Gold CPUs though and have never had any performance issues even with ≥1Gbps PepVPN through them and generally we build our VMs with 4x vCPU cores and 8Gb of RAM.