For that size tank I would suggest doing an 1-1/2" of Organic potting soil (be sure it's organic) and 1-1/2" of sand. Also keep some sand back so you can make touch ups after planting and if you ever want to uproot any of the heavy rooters like the sword.
I've only had overflows with sumps in my SW
reef tanks but know it will affect your CO2
levels, meaning you may have to run your CO2
higher than you would in a sumpless tank. You'll have to do some research on that problem.
What is your lighting going to be? If it's not high enough you might have trouble with the P. Helferi (downoi) as it needs at least medium light. It will grow taller and get leggy in too low of light. You also will need to consider a good fert dosing regime if your using CO2
. Although the rest of the plants you have listed will need root tabs as they tend to be heavy root feeders.