Renovating house...advice?

Hi! We are purchasing a home in Missouri and plan to fully gut & rework the house. It was built in 1951, about 1,000sf finished currently.  However, it also has a sunroom, carport, and attic space (no basement).  The idea is that we will rework the sunroom to have a laundry area and finish the carport space to be 2 miscellaneous rooms (hom3 gym, man room, etc).  The attic will be finished out to have a boys side & a girls side with a 3/4 bath in between.  By the time everything is finished, we are looking at roughly 1800sf.  We are planning to spray foam all exterior walls & attic space.  The house currently has no ductwork for heating/cooling.  This will be our family home, hopefully for decades after my husband and I are long gone.  We have 6 children, the house is on 80 acres.  We want the house to be as  efficient as possible.   Ideas for be8ng more sustainable in heating/cooling/anything else? Looking into RMH, but idk that it could heat the whole house?? We do have a wood cook stove, but other than that, it’s a blank slate.  Would like to be as off grid as possible, or at least small footprint, but doable as hubby and I get older.  :)  

TIA for thoughts/ideas,

Blessings,
Veronica

Solar PV is really cheap right now, but the price may go up in the future due to Tariffs, etc.  There is also a 30% federal Tax rebate available for Solar PV, that might go away in the future.

So bottom line, buy solar ASAP.

I installed a Pioneer 12000 BTU  Mini-Split heat pump last year, cost less than $1,000, I did the install myself.  
That plus passive solar heating were our only sources of heat this winter for my ~1500 sqft house.  The mini-split was surprisingly efficient, most days it used less than 2kwh worth of electricity, but it's much colder in the winter where you live so it would probably use more.  Your house is also larger, so 2 or 3 units, or one larger 'multi-zone' unit, but they tend to be a little less efficient.  

It kept the house much warmer than last year when we were just using electric space heaters, and they were using 4-5x as much electricity.
Here it only takes 2 solar panels to produce enough energy for the mini-split, maybe 4 to 6 where you are.

Off-grid sounds nice, but if the grid is already at your house, then a grid-tied setup is significantly cheaper (perhaps 20-30% as expensive as off-grid) and much more environmentally friendly.  You don't have to use batteries, you can get by with 1/3-1/2 as many solar panels (and still zero out your energy use) and when you generate more energy than you need, it goes back to the grid and powers your neighbors houses, so the central power plant doesn't need as much fuel.

However, some power companies are now charging their solar customers additional fees, which can offset the cheaper costs of grid-tied.  My power Coop is increasing fees on solar customers over the next 3 years, at that point I'll end up paying almost as much to be connected to the grid as I would if I didn't have any solar at all, and I push 2,000 kwh surplus power to the grid every year.

Let me chime in on potable water.
I wanted to go off grid for water usage, so I figured out what I needed for tanks and rain collecting surfaces.
It was too big for my little city property ,and cost too much.
I turned to conservation, and with a low flow toilet  and a high efficiency front loading washing machine,I cut my bills by 40%.
Now I can afford the tanks that would need to go off grid,because they are much smaller, and the savings on my water bill can go towards that project.

The lesson for me is reduce usage before you try to go off grid.

I love the idea of a laundry in room in the sun space.
A perfect place to hang the laundry, thus avoiding the cost of electric, propane or natural gas cloths drying.

I would seal that space off from the house when it's below 80° or so, and above 80° I would siphon off that heat to the rest of the house.
This could be accomplished with ducts,fans and snap switches (thermostat switches),or with more passively with green house vents.

Putting an efficient woodburner with thermal mass in the sun space could allow for solar gain,on the mass, and on firewood that's being stored.

If codes allow for a rocket mass heater, I would build an 8" batch box.
If not, I would buy an efficient conventional wood stove, and surround it and especially it's chimney pipe,with mass.


I would  be inclined to leave the carport as a place to store stuff out of the rain and snow, and build a pole barn, hoop house,  or shed for as a man cave.
Since you would be starting from scratch,it could be less of a compromise.
It could be where you mount your solar panels,and keep the batteries.
It could be home to a rocket stove, maybe powering a boiler.
You can build in a trombe wall,space for rabbits or a woodshop.

If you are willing to tear out ceilings,  this is a good time to run ducts,water lines , coolant lines, electric ,etc.
I would make these chases accessible by panels, to ease future remodeling.

Consider opening up doorways to accomadate wheelchairs,  and including a zero entry shower.

Plant something fast growing for shade, trees are a storm risk,  maybe vines on a trellis would be better.

Congratulations on starting your homestead!