Tent guesthouses are available at EBC (Everest Base Camp) and Namtso Lake.
The tent guesthouses in EBC are rectangular, black tents made of Yak wool with a few beds and small tables inside. All beds are covered with Tibetan carpets and can be used as bench seating during the day. Solar cells are the only source of electricity, so it might be hard to find a place to charge your electronic devices.
At Namtso Tashi Do Peninsula, there are both tent guesthouses and cardboard guesthouses are available for your option, so far both are clean but cardboard guesthouse is recommended as it is much silent at the windy night.