If you want to send midi out to the hardware, a good/cheap way to do it is with a midi CV converter like CV.OCD or Hexinverter Mutant Brain. They are basically same thing except the mutant brain is a module in the rack and the CV.OCD a separate box.
My advice would be to forget midi though and get a DC coupled (ie CV capable) interface like the Expert Sleepers Es/8 or 9 mentioned above. Now instead of sending midi and converting you are working with CV in both VCV and the hardware and can freely pass it back and forth between the two.
My other bit of advice would then be to focus your hardware on good analogue sound generators and processors - VCOs, filters, wavefolders, distortions etc and maybe some granular stuff and then do all you sequencing, triggers, logic, modulation etc in Rack - also come back into VCV for effects and mixing.
Watch some of Omri’s videos - he combines VCV and hardware really well.