Simple answer: You don't.
Carpet plants need a lot of nutrients. Fish are actually not very efficient at digesting nutrients from their food, even less efficient than we are. Thus, a lot of nutrients are in fish waste for plants, and it is an integral part of the planted tank's fertilization process. Thus, you don't gravel vac in areas of carpet, and let the plants absorb the nutrients. However, you don't want fish waste to clog your plants so they don't photosynthesize as well, thus the carpet must be disturbed by movement, from either fish or humans. Which is why fish like corydoras species, loaches, and algae eating fish like otocinclus and SAE are integral to a dense aquascape. They're constant motion helps to disturb waste from all the plants in the tank so it can become water-borne and be picked up by the filters. Human help should also be there; I use a long BBQ skewer to tap all my pants and disturb fish waste from their leaves and stems once a week.