With respect NursePlaty, I've grown HC, Glosso, Crypto Parva, Pygmy Chain Sword & Dwarf Hairgrass in tanks using plain gravel & gotten good coverage with no problem. The trick with these plants is to use substrate fertiliser tablets that are rich in Iron. API substrate tabs work well. Most people who don't have success with those plants in a plain gravel substrate either don't use substrate tablets (or the wrong ones) or the gravel diameter is too large. With anything under 1/8" (4mm) gravel & the right substrate tablets, they will grow just fine.
The WPG rule does not apply to T5HO lights. That rule was based around either T8 or T12 flourescents, (there's debate which one). Either way they have similar intensity output per watt. Seeing as T5HO flourescents have approx twice the intensity per watt, the WPG rule is useless with them. If you do want to try to apply it, you first have to double the wattage number & then divide that number by the gallons of the tank. So 2 x 54w T5HO is 108w, 2 x 108w (double the output) is 216w. 216 divided by 55 is 3.927. So this tank is much closer to 4wpg than 2wpg. At anything over 2wpg co2 is mandatory no matter.
Also worth noting that the OP is lookig for foreground carpeting plants & none of the ones you have suggested NursePlaty, are foreground or carpeting plants.