As C-Tran looks for ways to pay for operating light rail in Vancouver, an early analysis shows most of the recently explored options wouldn’t foot the bill by themselves.If they don’t pencil out, that would leave the agency right back where it started: pursuing a sales tax increase — and a November ballot measure — to pay for light rail.That’s the path C-Tran had long assumed until earlier this year, when Vancouver Mayor Tim Leavitt and others pushed for more study of funding sources that wouldn’t require a sales tax hike. Last month, the full C-Tran Board of Directors told agency staff to explore possible alternatives, while keeping an emphasis on a November ballot measure this year.C-Tran and the city of Vancouver have since looked at several possible options: an employer tax, a car rental sales and use tax, and a vehicle license fee among them. The agencies also evaluated using money from their respective general funds. In C-Tran’s case, that would require a change in board policy. Officials even included a “sales tax windfall” from the Columbia River Crossing — that is, using the extra tax revenue generated during construction of the $3.5 billion megaproject.By themselves, most of those examples appear to fall well short of covering the estimated $2.57 million annual cost to operate light rail in Clark County, according to a staff report form C-Tran Executive Director Jeff Hamm. An employer tax across C-Tran’s entire service district could collect as much as $3 million per year, but that’s a slow-growing revenue source not likely to keep pace with the rising cost of light rail over time, according to the report released Friday.