I think your approach of 'start simple and see what works' is a great way to go.
I have been told by people that you can dilute tea by up to 20:1, that is the model that the farm that I work for uses. When I make tea at home for the garden I water it full strength onto wet soil, meaning if it hasn't rained for a week or two (i live on the coast, we get rain more regularly than you all do inland) I water from the spigot before I apply the tea to ensure that the microbeasties have a good home to get delivered to.
It definitely helps to have the aeration at the bottom, You can just zip tie a nut or bolt or something to the end of your hose to keep it down. or use a produce twisty or something.
I can give you my loose recipe that I use, I brew tea in a 55 gallon drum with usually around 40 gallons of liquid in it
In the bag;
2-3 handfulls of compost
2-3 handfulls of worm castings
1 handfull of alfalfa meal
1 handful of bokashi
small handful of insect frass
big pinch of azomite/greensand
In the water;
about a pint of liquid fish (I actually prefer brands that have a diversity of sea life, you can probably find Pacific Gro near you and their good. crab, squid, shrimp, etc.. definitely seems to add to the finished product)
an ounce or so of humic acid (i inherited like 2 gallons of Anasazi Gold from a friend, I'm not at all positive I will ever buy more of this when it eventually runs out but I know that humic acid is used by commercial organic famers and I have it so...)
3-4 oz of SeaCrop - this is a sea water concentrate made on the olympic peninsula. I put it in my water and am generally convinced that it's amazing for supplying trace minerals. It can definitely replace azomite/greensand and there are other sea mineral concentrates you could use as well but I'm a bit of a fan boy of this one and the creator, Art Ziegler, wrote a great book called Seawater Concentrate in Abundant Agriculture where he goes into the benefits of sea minerals and talks about and tests other brands besides his own.
a cup or so of soluble kelp powder or 12 oz of liquid kelp
depending on the weather I brew this for 18-36 hours (longer in the spring/fall, shorter in the summer) and then water it in
These things are all in the recipe that the farm on work on uses and my measurements are all based on easier ways for me to remember the recipe. I don't think that everything in there is 100% necessary and at home I just use what is on hand. I will actually buy quality compost, insect frass, liquid fish, sea crop, and kelp. Otherwise I depend on kickdowns, 'expired' items from my work, and random late season sales at the garden store. I make bokashi sometimes and buy it sometimes because it is central to my home composting efforts.
For a 5 gallon bucket I would say use about 20% of the amounts in that recipe as a baseline and experiment a bit. Rich forest soil can replace the compost for sure.