Paddo, I'm in much the same time vs family situation as you.
I've managed to build Brewery v2.0 with large enough equipment to mash & boil triple (slightly concentrated into 17L fresh wort cubes) batches.
* 120L Plastic (HDPE) Storage bin, insulated with a camping mat, and Gaffa Tape
h34r: (Holds temp to within 1C with these large batches. Haven't used it during winter yet though!)
* 82L (20Gal) Stainless Brewery Keg
* 50L SS HLT
* 1x Three ring burner with adjustable HP reg
2 weekends ago was her maiden voyage.
Volumes with 14.5KG of grain:
Mash-in with 37L
Batch Sparge Round 1 with 15L @ near-boiling
Batch Sparge Round 2 with 30L @ near-boiling
Pre-boil Volume at 70L
Efficiency into Boiler was apparently 77%, so very happy with the first results.
I have a very very basic setup. No fancy brew stands or pumps or anything like that.
* I use my outdoor Keg fridge to hold the mash tun above the boiler level.
* I get the main volume of my strike water into the tun from the hot water tap @ ~60C, and top it up to the correct strike temp with boiling water from the HLT, sitting on a converted webber BBQ.
* I use 20L plastic buckets to transfer the sparge water from the HLT at waist height to the mash tun on top of the fridge.
* I can then gravity feed the wort into my kettle, sitting on bricks on the BBQ next to the fridge.
If I could change one thing, I'd get an immersion element for the HLT. Having only one heat source is a bit of a pain, but it just means that I have to wait for all the sparge water to be used before I can transfer the 3ring burner and fire up the kettle.
So it can be done with relative ease and minimal cost. Finding a
large enough boiler will be the trick to your success.