Welcome to the forum.
I would tackle this a little differently. I am going to assume you have no equipment. I am also going to assume you don't have a huge budget and will be buying used lower capacity farm equipment. I could be wrong though. However, if you are going to do a viable and profitable business plan, starting with lower cost equipment would be necessary or you would need 500 acres of alfalfa to get a decent return on $300,000 in equipment. Having assumed all of that, I would suggest that you pick out a 9-10 foot DiscBine at $9000+, a V rake at $6000+, a tedderer at $5000+ and a good Small Square baler at $12000+ and a used 90 Horsepower tractor at $25000. Basically, pretend to build your equipment list and estimate your working times from the equuipment you will be using as a realistic estimate. Tractors have fuel consumption specs listed in various places, but TractorData.com has most of them in one spot. You will run the throttle full on mowing hay but maybe half throttle on raking hay and tedderering, then back to full throttle on baling hay. Balers also have a theoretical hourly bale limit listed in specs. So, you can estimate fuel consumption and bales per hou once you know your equipment. Of course, another thing that comes up is what equipment to get. Again, I would point to dealers in your area and get that kind of equipment because you will break down and need parts, even if you are a mechanic. Moving and transporting small squares has to be automoted now days so you must factor in an accumulator $15,000, a Grapple $6,000, a skid steer at $20,000 and a bunch of long wagons at $3000 but preferable to have goosenecks at 25+ feet at $10,000 each and a pickup to pull the goosenecks at $20,000+.
As I do a fair amount of Alfalfa, it does have some quirks to it that general grass hay making doesn't, mostly leaf retention and good color. Given that you are out West where things are arid and dry, you won't run into the same things I do, but maybe different things. An example is that I try to never rake or tedder alfalfa when it is dry, but I get dew in the morning to pull off that practice. You may not get dew and need to do things at night. Making a good Alflafa field is not just selecting good soil but prepping it and planting it and fertilizing it. You will have to pay someone to do that if you are starting with nothing and creating a new stand. Your seeding costs for Alfalfa which should be in your business plan is significant, but really significant, if you fail to get a good crop. Been there and done that.
If you average 75 bales per acre first cutting, 40/acre 2nd cutting and 20/acre 3rd cutting, that gives you a maximum amount of 135 bales per acre and gives you a maximum amount of 10,800 bales. Out west, that figure I am using might be way high, I don't know. I get a lot of rain and this is what I use. If you charge $10 a bale, $108,000 total revenue is the best case scenario on yield. I contend that you will need to spend $100,000 minimum to get the equipment to handle 80 acre field by yourself without hiring anything done. You will need probably more than 80 acres out west to pay for the equipment and a decent salary. If you amortize the cost of $100k over 7 years (a figure allowed by USDA) you would have a yearly payment of $20,000. That isn't insurmountable figure. However, your actual average annual yield is critical and something none of us can project. Most local USDA offices have a figure they use to estimate yields at the local level so I would recommend starting there or asking someone who may be your competitor in the area what they do. Alfalfa is intensive on water so make sure you have plenty of it. I actually do a projection every year and have been tuning them. I now expect a 15% loss on rain or other factors. USDA has some forms that you can use and that are accepted by banks to do your projections. We all hate the government until we need their help.
You are actually the second guy I have run into on the forum that is starting haymaking at 60 which is commended. At the same time, there are many at 60 getting out of it. No help left on the farm, equipment is worn out, land rents are outrageous, etc.. Cows and horses and livestock have to eat so we all can't get out of it.
Good luck and share some more so we can suggest better solutions. I want nothing more than to see you successfully make hay at a profit.