Roughly this is what i had in mind,
1. Prepare separate network (with specific block weight).
2. Prepare few fast computer solely to broadcast transaction & mine block.
3. Prepare few cheap/low-powered/old computer (e.g. Raspberry Pi and old Intel NUC) used to perform benchmark.
4. On fast computer, perform mining block and broadcast transaction (on various network load such as 25%, 50%, 100% and 125% of block size limit).
5. Measure time to verify block/transaction and CPU, RAM and I/O usage on other computer.
You do not need separate computers for the benchmark, for more reliable access you can spin up virtual machines and selectively limit their RAM and CPU usage. You still need to get separate HDD and SSD disks but these can be passed through via PCI to the VM (I assume internet speed is constant, but even that can be throttled using different virtual adapter types).