Should I go brackish for the red claws or rethink it?

about 2 weeks ago, I bought 3 Red Claw Crabs on a whim and without a tank. The guy at the store said they'd be fine in a bowl.. Petco... wrong

I decided to build a proper crabitat for them, and really went to town over the last week,,, and now have a really nice, small, biotope that consists of:

20 gallon, half full tank
Eheim 2213 canister filter with wood as water fall
about 2 gallons worth of large rocks forming a multitied cave structure
mixed planting gravel and medium stoney gravel
fully submerged titaniam heater
“home brew CO2” system to feed the plants
several types of plants native to South East Asia (most that crabs don't like)

everything is going smoothly. the crabs really seem to love the environment, spending hours sitting in the water fall showering… tons of great hiding spots to tuck into. they haven’t really bothered the plants, as hoped, and even seem to go after a few dead spots on the plants, helping me garden. I like em.

here’s the catch: because I only have about 10 gallons of water, I am limited to my fish choices. on top of this, the crabs were sold as fresh water, and seem fine in it, but are actually brackish crabs. I’ve read varying opinions, but most seem to think that the crabs will live in fresh water, but may not live out their full life expectancies, and I read in one blurb (and only one of hundreds) that they might have issues during molting.

So, I had set out to build a mildly brackish SE Asian estuary, on a mini scale.

From the plant guy: nothing likes brackish. (contradicted online by a few people who have done what I want to do on a larger scale)

Then I start thinking about the rest of the tank mates… for 10 gallons, there are few options. For fresh/brackish fish that can do either,, even fewer. Algae eaters that fit the tank and category even fewer. The best candidates being Loaches, most of whom like crustaceans as well…
After all the research, I had decided to try and set up somethingg with a small school of Rasbora, Danio, Glass Fish or Minnows, with maybe 2 larger, but dwarfed fish like Pygmy Gouramies (which croak when they mate!) This didn’t really solve the algae problem. I thought maybe I’d get a few small barbs instead, since they eat algae a bit… and all the choices fit the South East Asian environment, and all can be transitioned to brackish, so I had read.

Today I called the fish store I like to deal with to aask about some eggs I found on a leaf from one of their plants (took them out) and I asked about the algae eaters etc… and he reccomeneded Ottos, Otocinclus, in a small school. They are algae eaters, but mini sized at about 1 inch or so. from BRAZIL… and I didn’t see anyone mention their tolerance to brackishness… They look perfect in terms of size and function, but they defeat the two original goals. And, the guy said they are small enough that the crabs might tryy to eat them. (which I’d risk)

question 1:
Should I bother with a brackish tank with plants?

question 2:
Am I foolish to center the tank around the crabs when they make everything else more difficult?

question 3:
Am I asking too much to try and make it so authentic to the region?

well, thanks for the overwhelming responses! lol. I took a few photos tonight after adding 7 Cherry Barbs.