New instance(s) setup question

Probably pretty basic, but a quick question for a new installation. Oracle pricing has really gotten out of hand, and my Center is drastically downsizing everything to save on costs. We also have several security things to address, and multiple people retiring in the next year or so, so we also have an emphasis on getting things simplified and documented for fairly new and inexperienced SysAdmins, DBA and devs.

Anyway, the SysAdmin has setup a new server for me to migrate all of the Oracle stuff to. It is an
 Intel Xeon Silver-4112 2.60 GHz Socket/Processor with four (4) cores and 32 GB of Memory, running Windows Server 2016 Standard.

The C: (SYSTEM) drive is a mirrored volume consisting of two 1TB SSD drives with NTFS space of 884 GB. The E: (APP) drive is a mirrored volume consisting of two 4TB SATA Enterprise drives with NTFS space of 3.45 TB.

Now my question is How to get Oracle setup on just this one machine, with both my production and development databases. Should I go with two separate installs (instances), or just go with the multi-tenant and have two pluggable databases? The production database is roughly 1GB in size, with maybe 3-4 users per day, and a total of around 150 users, so performance and throughput, I/O, etc. are extremely minimal. But with myself (hopefully) retiring within a year, and my current backup seeming to be out of her league and not being very motivated to pick up the reins and charge ahead, I want to keep as much as I can, as simple as I can (so I have less documentation to write).

At this point in time, I don't have much confidence that she'll be up to the task of taking over if I do retire, especially if I pick the more complicated maintenance installation option. So I'm faced with the prospect of two installations, which is what we currently have with two separate servers. Or, I could go with the multi-tenant option and have two pluggable databases. But that approach has me worried about future upgrades, etc. That will add a whole new level of "stuff" she'll have to learn and for me to document. I'm also worried about availability in case somehow the root container gets hosed and she need to perform a reinstall or anything else that would probably bury her technically.

Any opinions other than hiring someone with more motivation and more experience? We are a government agency, so hiring somebody with the skills at our pay scale is pretty far-fetched, especially when management doesn't think we deserve what little pay we do get. Thanks.