Hi @extramileit if your VPS seems to have more than enough resources for running 2 instances of the Cardano node. I manage to run a testnet relay and a bp node on an AWS EC2 with 2vCPU and 4GB of memory, I’ve also added a 4GB swap. So when running the node and relay you can run in different ports. For example 6000 for the core(bp) and 6001 for the relay.
When binding ports what I did was only to bind the relay nodes port to be reachable via the internet and the core node only bind to 127.0.0.1 as it only needs to be connected by your relay node only.
For your topology files you can use the local (127.0.0.1) address, however, you have to bind your port to IP address in relay node so other relay nodes can connect to your relay node.
Something I observed is when you first start the node it needs a lot of CPU during the db sync and after that it needs more memory and less CPU. So since I can easily upgrade resources in aws I increased my number of CPUs until the db is synced and downgraded back to lower specs to keep in running, So when I monitor my node now I see less CPU utilization and high memory consumption.
Hope this is helpful