A mounting system for securing a base plate of an access device within a vehicle includes a plurality of lateral clamping beams configured for attachment to a tracked floor in an orientation in which each of the plurality of lateral clamping beams lies across a plurality of tracks in the tracked floor. The plurality of lateral clamping beams includes a front lateral clamping beam adapted to overlie a front edge of the base plate, and a rear lateral clamping beam adapted to overlie a rear edge of the base plate.