Haas are last in the Formula One constructors' standings and team boss Guenther Steiner (58) has let the pair decide their own aerodynamic packages for the Saturday night spectacular.
"Nico feels that for him the old spec suits him better, and Kevin is the opposite," he said.
"We’ve opted to give them what they want, we have two races to go and nothing to lose, so we’ve tried to do what we can.
"We could discuss gathering data, but we’ve got enough data, it’s a decision based on what each driver likes more than anything else. It puts them in a comfortable position so that they’re as happy as they can be with the car they get."
US-owned Haas are four points adrift of Alfa Romeo and nine behind Red Bull-owned AlphaTauri with only Abu Dhabi to come after Las Vegas.
The night race is a step into the unknown for all, with temperatures expected to be as low as five degrees Celsius and racing on a 6.12km track that drivers have tried out only on simulators.
Hulkenberg suffered excessive tyre wear at the previous race in Brazil, with both cars also involved in a first corner collision.
"Getting the tires up to temperature is going to be very difficult. We could see some spectacle - it’s going to be all about getting temperature in the tires. Downforce helps with that, so let’s see how we go," said Magnussen.
Pirelli's motorsport head Mario Isola said he expected the weekend to be "a major technical challenge" for the manufacturer, who have brought their three softest compounds, and teams.
"The surface will be a mix of the usual street asphalt, especially on the actual Strip, as well as other parts that have been completely re-asphalted for the occasion; adding another unknown element," said the Italian.
"There won’t be any support races and the track will be opened again to normal traffic for long chunks of the day, which means that the surface won’t rubber in as usual and deliver improved grip.
"Those long straights also make it harder to warm up tyres in qualifying, as well as keep them in the right window."
