I've kept bare bottom tanks with high grade shrimp by using the method you mentioned. 100% RO, remineralized to optimal TDS range.
You have to be certain your RO filter'd water is as close to 0 TDS as possible. Some folks use store bought RO water where the store filters are near their change date and aren't filtering the water as well as they should be. Others who own a RO unit just get lazy/oblivious of changing their own filter cartridges and let their TDS get too high that way. Don't be those individuals
Dependant on your shrimp bio load, If bare bottom is the route you want to take, you have to maintain at minimum, weekly 20% water change with new 100% RO remineralized water. The less shrimp you keep, the less water you'll have to change. Lotta work involved, but it works.
As far as substrates go, I like to redo my tanks once every 4-6 months with brand new soil. This gives me the opportunity to clean out the dirty/clogged filters/sponges as well. Shrimp love brand new tanks
. Just makes sure they're cycled properly first, depending on what type of substrate is being used.
Other folks may prefer to do things differently, so do take my methods with a grain of salt.