Wynmark Development Corp. plans to sop up some of the gravy generated by the new Potomac Mills outlet mall in Prince William County by putting up a low-rent, no-frills, "limited service" Days Inn Hotel near the mall.

Richard Naing, 34, president of D.C.-based Wynmark, said the $8.1 million, 175-room hotel will be built off Neabsco Mills Road at the junction of a planned, as-yet-unnamed, street leading to the main entrance of Potomac Mills. At nine stories, Naing said the new budget hotel will be Prince William County's tallest building. It's being financed in part by $6.4 million in Prince William County industrial revenue bonds authorized by the state of Virginia, he said.

Wynmark expects to hold room rates to between $34 and $49 by dispensing with large furnished lobbies, expensive restaurants, bars, convention facilities and most other services. Guests will be treated to a complimentary self-service continental breakfast of coffee, rolls and juice in a first-floor lounge and there will be vending machines on each floor for ice, candy and soft drinks, Naing said. He said guests likely will dine at nearby mall restaurants and other eateries that will spring up as part of the burgeoning development in the Dale City-Woodbridge-Lakeridge area. Like Potomac Mills, an unusual mix of traditional discount retailers and off-price factory outlet stores, the hotel is "a new concept," Naing said. "Basically, we're eliminating food and beverage services" that add significantly to the overhead, while keeping the quality of higher-priced hostelries, he said.

Rooms at the planned Days Inn, which will have a swimming pool and small playground, will be "as luxurious as those of the Hilton or Sheraton," Naing maintained in an interview. "We can offer those rates because we don't have to subsidize room food services . . . no late night shifts in the kitchen."

Naing said the hotel expects to do a brisk business from tour groups coming to bargain hunt at the mall. "And the nice thing about this hotel is that we really don't expect we'll ever have a slow season," he said, noting that many hotels suffer a slowdown during winter. "November, December and January are great shopping months, and we expect shoppers will come to the mall. We also expect to benefit from the tour and travel industry and we have all the I-95 traffic."

Naing said Wynmark Development, which operates The Convention Inn TraveLodge in downtown Washington, has formed a hotel management company to operate the new Days Inn, which is scheduled to open in December 1986. Naing said Wynmark has plans for another budget Days Inn in Oxon Hill.

Western Development and KanAm Realty, the partners that are building Potomac Mills, have tentative plans for a 200-room upscale hotel and convention center across from the mall at Gideon and Smoketown roads. But Naing said he thinks there will be room for both his Wynmark's budget inn and the full-service hotel, with its higher room rates and more luxurious amenities.

"There are different categories of travelers," Naing said. "There's the executive who wants to stay in a suite and there's the families who want to save money. We can do very well with the traveler, the buyers for the stores and the shoppers, tour and travel group. Those people are very rate sensitive."

Officials in Prince William County's Office of Economic Development said Wynmark's inn will be the first such budget hotel to be built in the county in recent years and that several other developers have filed for rezonings to build other such hotels in the near future.