Is it possible to save/cache a simulation to disk using a DOP I/O, close Houdini, then open the same project later and load the simulation from the cached files? I'm able to save enormous data out but the DOP I/O never loads from file no matter what settings I use.

Did you check “load from disk”?

Sorry for the late reply I finally figured how to find my posts in this forum.
Yes I've checked Load from Disk and it still cooks when opening a previous hip file and running a simulation with saved simulation data.