If me, I would put a container onsite and secure my tools there. Downside is the extra travel/work when you need the tools at home. Sometimes I have time/energy to do a task, but if you add additional time/travel then miss that opportunity.
That is why I have about 3 full sets of tools. Every time I was working out of town, I bought a set of tools to keep there. Nothing wrong with having too many tools though. I also now have 3 rolling cabinet tool boxes to keep everything in.
When I bought the land for my retirement home, the first thing I did was lay out where I wanted my house and shop then hired a dozer to level the area. The land then set for a couple years and all the dirt settled in nicely. I did have to do some more levelling with my tractor because my proposed shop location got compromised with an overhead electrical line so I had to back it up 50 more feet. This worked out for the best because it gave me a bit more turn around room which I now need for my motorhome.
I regress: After a couple of years of planning and design, I had my shop built, a 52 x30 foot structure. A few years later after completing my house and moving in, I added on another 30x14 wing. It seem you can never have enough storage/shop building.
Build any outbuilding twice as big as you think you will need.
So, my suggestion is to go ahead and plan your site layout and at minimum put a container on site to store your tractor and some basic tools in. I would get a 40 foot rather than a 20 BECAUSE my experience says you will end up filling it with tools and equipment and may even need additional space. If you have the land area, put the container way off the road and back in the trees, hidden as much as possible and for sure completely out of your way of future building.
Just don't get it so far from your future house that it is a PIA to get too. The walks get longer and longer as you get older and it could be expensive to move that container later. A CUT or even small utility tractor isn't going to be able to move it, maybe a small dozer could drag it around a bit to relocate it.
As I said, I elected to just go ahead and build my shop in the spot chosen since I needed the storage anyway. That was the best $30K I ever spent. When my Crosby house sold (I had to sell it prior to building my retirement home), I rented a house for a year and much of my stuff wouldn't fit, so my shop became a storage area for my boat and dozens of boxes of "stuff" that would not fit in the smaller rental.
Costs continue to rise for building materials so anything that you can afford to build now is going to be cheaper than it will be several years into the future.