How many kW are you planning to draw? It can be anything from easy to impossible depending on your answer.
Keep in mind that commercial leases require you to restore the building to original condition if the landlord wants. Cutting holes can get pricey. And leasehold improvement laws mean that any electrical work you do stays with the building.
For any scale that I find interesting these days this means buying the building. Most upgrades to make a building suitable for serious mining will cost more than the property itself.
I was going to use an 800-1200A panel. I am meeting with the owner tomorrow to get all the lease details. I do not mind paying for a panel upgrade and I do understand that I will need to reverse any changes that I make. That's why I was looking at just modifying the roll-up door.
You're right it does take a lot of modifications for airflow and cooling and makes buying more attractive. I am just not sure I'm ready for the initial outlay, I hope to find a sympathetic landlord.