@Henry Clark thanks for putting so much detail into these posts. I learn a lot from reading them. I would love to develop something like this, but east coast land availability, zoning, and prices make it prohibitive. But even with your low land prices, I'm amazed that you did all this with only $200k into it. That's about how much cash I have to play with right now, would love to think that I could turn it into something as big as what you're doing.
One reason I want to get into this kind of space is that I make stupid big art. Last piece I made I had to go from Boston all the way to Philadelphia to find a place to finish the project. Me and the gang work in metal. We know how to keep the outside of a place clean. I say let the welders play, just be strict with them about not having the place turn into a junkyard.
Having worked in all kinds of shops, I can absolutely 100% say you need private bathrooms in each unit. Slop sinks, too. And in some cases, provisions for emergency eyewash or emergency pull chain showers. Shared bathrooms will get nasty in a hurry and no one will want to use them. Do you really want to have to pay a maid to come in daily and clean contractor bathrooms? Just make sure you make everyone sign some airtight documents about what they're allowed to dump down the sink drains and that they know if they break the rules the legal liability rests with them. Just stub in plumbing and drains on one wall in each unit and let the tenants decide what they want. Some may want two toilets, or his/hers bathrooms, or a shower, or laundry. Make it easy for them. PEX and PVC are cheap, this is no place to cut corners.
As for electric, more is better. Especially since we are coming to a future where people will soon need to be charging electric cars at their workplaces. Minimum of 200 amps to each unit, 400 might be nice to offer, if you can do 3 phase 120/240 that will be better, separate panel and meter for each unit is a necessity. Yes this adds up. Yes, it will pay for itself. You will get a higher rent and have a bigger tenant pool if you offer enough electricity for people to run all their tools. And with all electric F150s, Hummers, and Tesla Trucks coming to market in a year or two, you want to be ready for people to be charging those at their workplace.
For insulation, it is time to see the writing on the wall. Energy efficiency is going to be a big deal going forward. Do more than the bare minimum. It will save your tenants money on their electric heat and AC, it will keep the noise between units down, and it will keep the units more comfortable. All of which equals higher tenant satisfaction, higher rents, and lower turnover. I work with a wastewater utility up in Maine that keeps a chemical storage garage heated to 50 degrees all winter long with no fuel cost. They super insulated the walls, put radiant heat in the slab, bought an extra insulated garage door, and stuck two black solar thermal panels on the roof. Sun hits the panels, glycol gets hot and goes to a storage tank inside, then into the radiant floors. No boiler, no furnace, no cost for heat since they built the building 17 years ago. In Maine. It can be done. It's just a cinderblock building with lots of extra insulation, doesn't look any different than any other new garage. Extra costs for insulation are offset by reduced costs for HVAC equipment and ductwork.
Not sure about driveway widths but 50' sounds tight. My sprinter is over 20' long and doesn't turn well. A lot of these guys will be driving 4 door pickups with utility trailers. Make life easy for them.
For lights, see if your electric utility has any incentive programs to get you rebates. LEDs are great, but they leave dark spots if you don't have enough of them. Nice to have them on multiple banks so you can either go full brightness or just 1/2 bright if needed. And everyone likes natural light, so if there is a way to incorporate a big picture window into the front of each unit or put in some solar tubes or something, it will be a nice touch.
Lease terms seem short to me. This isn't self-storage or residential. I would want 3-5 years, but you can experiment.