San Diego The Sycuan Indian band, proprietors of a casino on their reservation in the hills east of El Cajon, has become a major backer of San Diego mayor Jerry Sanders. Campaign contribution records show that the tribe gave a total of $20,000 to San Diegans for City Hall Reform, the mayor's recent privatization campaign. Meanwhile, in Sacramento, the tribe is lobbying hard for legislative approval of the governor's award to it of vastly expanded gambling rights, including 3000 new slots and a second casino to be built on the tribe's nearby golf course, formerly called Singing Hills, a move opposed by neighborhood groups concerned about heavy traffic. Now Sycuan is fighting back with TV commercials that feature a beaming Sanders praising the tribe's "leadership and generosity," which, he says, "positively impact the entire region." ... Meanwhile, at Carlsbad's luxury La Costa Resort and Spa, once the getaway of choice for the Mafia, the Teamsters union, and Richard Nixon, another interesting bunch reportedly showed up last week. According to the Desert Sun of Palm Springs, incoming state legislators were hosted by "unions and racetrack operators," who were lobbying against approval of those new Indian gambling compacts.