rjxj, I am finally looking at your drawings on my laptop (could not see them on my phone). Yes! the top one is just what I had understood from the convo here (and was thinking I should draw and post to ask if I had it right). I am so excited to see that my understanding was right -- I feel much less clueless now :).
The only thing I would add is that I feel I want switches to shut off, individually, the inverter, charger, etc. So I would put breakers instead of fuses. I do not have any particular reasons in mind... I just feel I want to be able to quickly and easily get these high powered items out if their magic blue smoke starts leaking.
So I need a little box for 6 or so breakers, might as well do everybody.
I am also still confused about when I need a + or - buss bar, or both.
For the engine jump and isolator, I may be able to reuse the fancy solenoid from my current van, where I had a pro install. I just had him give me an anderson for the jump, tho. A push button would be fancier...