I'm impressed with your fat loss -------- two things need congratulations. 1. the discipline and will to have done what you planned and 2. your calculations - that I thought was really well done.
As you know - I subscribe to the theory -------- fat loss is all about diet (100%) and for everything else - it's exercise.
I won't give advice because I'm no expert - but, I can tell you some of my experiences.
If I had dropped 20kg of almost all fat and I got up to about the 10km a day walk mark - the latter of which I did do (early on) -
what I can say is that the body after years of what is truthful abuse - is going through a change - a transition period - and, there's a couple of dangers there.
Whilst you've stopped carrying a full 20 litre jerry of water - underneath the bonnet - is still the same - and, will take months to adjust.
So - for me - I should have checked the soles on my shoes and made sure that my wear was close enough to even - shoes begin to wear quite fast when you put on the kilometres - and, dropping off 20 kg - mostly on the front bit - your gait will have changed - so - in my case - I should have watched my shoes better - because I ended up with some sort of injury to ?? a hamstring I think - it wasn't a big boys hamstring problem you hear about - but, it pulled me up for several weeks.
Then, feeling like superman unleashed - I really should not have put the full weight on the arms and things as if I was still 20 years old swinging through trees - that blew a hole in my bicep -- about 18 months - and, I'm only testing how healed that is now.
Shin splints I've covered before.
When I did my first 50 km walk - that was probably reasonably wisely done. Because I'd been walking consistently about 23, 24, 25 km a day - with the odd one up to 30 - and, I thought - well - if I do a morning walk and I do it again on top of that ----------- that sounds doable without any fuss - and, so - it was.
I pulled up from the 50km walk - with all the important bits - fuss free. A tiny bit of muscle stiffness - but, really nothing.
The only issues were that I chose a day that was a bit too cold for it - it was sub zero and my hands got quite cold early - in light gloves, - I changed to heavier. But, a 4 or 5 degree start day would have been better. I also wore the wrong socks and managed to grind away a bit of my heel - but, no big deal.
The point is - that I was only doubling what I was doing easy anyway - whereas if I'd gone straight from 25km - to 100km straight up - well - that would probably not have been wise.
My lessons really have been - build steadily - and, don't be an idiot - there's a big difference when you add on 20 or 30 years. If one gets a warning from the body - ease up until you know what it's saying.
There's a fine line between a niggle and a break - I found.