About 350 anti-nuclear activists trying to salvage a faltering cross-country trek for peace left their desert tent city and marched 10 miles through pouring rain to a new campsite in Barstow. The group is the remnant of a band of about 1,400 people who set out from Los Angeles on March 1 for Washington to dramatize calls for global disarmament. On Friday, David Mixner, leader of PROPeace, the group that organized the march, informed volunteers that the enterprise had come to an end because there was no money to continue. Some of the remaining marchers want to take buses to Las Vegas to drum up financial support. Others, however, are insisting they must walk, saying that to take buses would be to compromise the original goal. Once in Las Vegas, the marchers plan to hike north to a federal government nuclear test site in Nevada to protest the testing of nuclear weapons.