I usually just use my Apple watch, wear it to bed to get my HRV. I had to use a program called HealthFit to get all the different data to TP, it works great. Besides my HRV, I get sleep and weight from my wifi scale. It will work with a lot of devices including Garmin and it’s free!

The 7 hour video series is a very good intro to the methodology for any endurance sport, don’t worry about mountaineering specific at your stage of learning, and it is cheap! However you need the book as backup reference material. I watched it 3 times and referred to the book repeatedly while trying to understand the concepts well enough. This is a very inexpensive way to get an introduction to the methodology. The training plans are cheap as well. There is plenty of articles and podcasts here to help you modify one. If you can’t afford a trainer you can get there, it will just take more effort.

Now to the real issues:

I am 65 and holding mid 80’s on TP. This is after about 2 years of effort with a long history of aerobic and strength training (not always the correct training but consistent over the years). So first I would say that is an aggressive time period. I am training about 12 hours per week to keep that number. By the time my rest day comes I am beat. We don’t recover nearly as quickly. So first question is given your BMI can you really ramp up that much training while trying to maintain a calorie deficit at 60? Trying to lose 30+ pounds in 9 months (based on your original post date) while pounding out the hours is a misery and very demotivating. It will really mess up your recovery. Second, how aerobically deficient are you? You need to baseline your current AnT and see if you are within the magic 10%. If you are really deficient it could take a long time before you can start doing enough hours to really knock off 30 lbs. Unfortunately AeT work does not burn calories very fast. So you have to put in lots of hours, but you are probably not ready to do 2-3 hours a day I would guess.

You don’t really need a special plan for age, you just have to realize it is going to take much longer to get to your goals than a 20 year old. You can do it but I would say more like 2 years, not 9 months. After 2 years of work I did Aconcagua and it was a great experience. Started out with 5 other members in our group, all in their 30’s and only myself and one other group member summited. This stuff works, but over 60 just be patient and have realistic goals. Cheers

The 24 Week Mountaineering plan at it’s peak only has about 14-15 hours per week. 12 hours per week was good enough for Aconcagua, but that is a non-technical peak. Before I left for Argentina here is what I was doing per week:
5 hours of sub-AeT cardio with a pack with 20% Body Weight.
3 of strength training/stretching.
1 hour of Muscular Endurance.
One 2-3 hour run.

It took me about 2 years to get to this level.

If your climbs will be technical, it will probably be more. Here is my experience. For the older athlete to climb big peaks with moderate technical work, we have to hit a higher level of fitness to achieve the same results that a younger person would. From this post: https://uphillathlete.com/mountaineering/fit-to-climb-everest/#:~:text=To%20climb%20Denali%20you%20want,of%20125%2B%20for%20three%20months

Scott gives examples of what it takes to climb Denali and Everest. For Denali they have a benchmark of 75 in TP. I know from experience that even with my current score of 85, I could not climb Denali. When I summited I would guess I was training about 20 hours per week and was 15 years younger. So I would guess that my fitness was approaching 120 in relative terms. Back then there was no TP. So I would guess add 20-25% more to achieve the same results that someone in their 30s would and then add a factor for the technical difficulty. I wish they would show us the TP Performance Management Chart for Art Muir, the 76 year old that summited Everest in 21. Be interesting to compare. Not trying to depress you, just being realistic. Steve’s most recent podcast again emphasizes there is no quick route to fitness.

I don’t think the summer with unlimited time will help. Unfortunately your body will only accept so much stress before it breaks. There are several good Podcasts on this subject. Being at altitude just makes it happen quicker. Problem is that when you are climbing you are withdrawing from your fitness account, much as you would money from a bank. If your climb is technical/difficult/high altitude (i.e. not a trekking peak) you will run out of “money” and depending on where you are on your climb it could be dangerous. It is unreasonable to assume that you gain fitness while climbing!

To answer your first question, as a compromise, I would try to lose at least 15 lbs before I started a lot of training. Then accept the rest and work on your fitness. Merry Christmas, although I feel like the Grinch.