Ben,
O.K., now I understand what you are asking about. It was not clear to me at first.
I think the suggestions still apply, but now you have to look at things as the studio owner, and think more about the demand side of things so that you can create the supply of space, gear and services to meet those hopefully growing demands. While the concept is a good one, I am sure you realize that there will be a significant shift in priorities, approaches and financial commitment. As to where to go to get the information, I still think it valuable to look at existing operations wherever, to get ideas of just how busy some places may/may not be. Also worth looking at the type of gear they are willing to offer, as well as support and other key issues. From there, it may be worth contacting some of the equipment folks to see what sort of terms they are dealing with, regarding usage, turnover experience, financial commitments, etc.
One thing for pretty sure is that there will be a major financial commitment on your end, and you should plan for that for several years, not just a few months. By getting some idea of rental costs on gear from other places, you will have some idea of what the market is expecting, and may use that to help plan your amortization costs, etc. For example, if you plan to become a higher end operation, you will need more higher end gear, and may get to charge higher rentals to help recover those costs. Conversely, if you shoot to become a relatively less costly alternative for photographers, you may be able to recover costs with more rentals, but you may also have to replace gear faster from use/abuse. The manufacturers can give you better ideas about warranty service support, as well as frequency of returns. You can keep things into different categories also....gear that stays in your studio only, and that that folks may take to their location shooting. Insurance coverage for replacement costs plus out of service can be broken down and applied to rental fees, but those will be determined by number/frequency of rentals, which you may not yet know, but is important to your best estimates in constructing your business plan. One way is to create an arrangement where you lease or lease/purchase gear from the manufacturers yourself, until you are able to better gauge use/rental.
I still think it valuable to talk with the guys that are in this business wherever they may be. If they are not seeing you as a direct competitor, they may be willing to share some deeper information. You can always also consider different business arrangements with them, like cross promotions to help enlarge both operations. I think the key is still trying to estimate the rental demand, and you may want to start with a narrower initial plan, and grow from there. Something like studio settings for weddings and portraits. You have a pretty good idea of what may be needed to accommodate the various group sizes, backgrounds, lighting, etc., already, and can then calculate the kind and amount of equipment and time needed. If you create a white room with several light stands/heads/softboxes/packs that can be easily moved into place, it may be relatively easy to generate customer traffic. Same can be said for portrait shooting. Once you get beyond that, the equipment needs and space can grow rapidly, such as may be needed for large products (cars), needs for "props", painting/repainting walls and even floors, etc.
From the equipment rental side, you will need access to enough gear to cover the demand. That may mean many light sets to accommodate those shooters all doing weddings those same weekends. It would be good to create some tried and true portable rigs that are easy to haul around, set-up and use. Again, you may start with a few sets, and grow into a larger collection of things. It will be good to know how many photogs are in your planned area, the kinds of shooting they do, and what you could offer to them that they might not have themselves to use to improve and grow both of your businesses.
Sorry to ramble on, but there are so many things to consider, and I am not sure what your plans really encompass (scale, direction, etc.) If I were going to undertake this sort of thing myself, I know I would be talking to as many equipment folks as I could, asking photogs what they would like/need, thinking about location, building business plans for a step-wise growth, talking to insurance folks about coverage of gear/facilities, and also thinking about the target market and marketing efforts to get the entire thing off the ground. Have not even started to think about cameras/lenses that may be the most common/useful for folks to rent or use, and that could become as important a business.
All of this has to be looked at as a business, and not really as photography anymore. While you can bring a lot to the party from your own experience, success will come from successfully marketing and supplying things at prices that attract and serve the target group. (I live in an are where there is a lot of sports activities, yet there are only on or two places where I could go to rent a sturdy, fast camera and big lens to shoot. Most photogs wind up buying their own gear to use. Same is true for wedding shooters here. On the other hand, there are a few very nice studios that rent space and have gear for photogs doing more specific shooting, like portraits, commercial products, even music videos. Stuff that most photogs would not have on their own, but could use several times per year/month.)
LJ