The coupling in fluid-structure interactions is governed by the pressure distribution over the interaction surface between the fluid and solid domains. The capability of non-intrusive optical techniques such as particle image velocimetry (PIV) and Lagrangian particle tracking (LPT) are proven to provide accurate surface pressure information over solid boundaries utilizing the flow velocity and acceleration, while simultaneously tracking the corresponding structural deformations. However, due to the non-uniform spatial response of arbitrarily shaped solid boundaries, these available approaches lack the necessary surface definition fidelity to ensure accurate numerical discretization of the pressure gradient integration. Therefore, an alternative surface pressure reconstruction scheme utilizing LPT data based on Arbitrary Lagrangian-Eulerian (ALE) approach is proposed to mitigate the associated the error propagation. The introduced method provides an exact surface conformation utilizing boundary fitted coordinate systems and radial basis function (RBF) based mesh deformations which eliminates the need of using extrapolations for obtaining surface pressure distribution. The introduced approach is assessed by means of an artificial hill surface probing a three dimensional analytical flow field and the practical applicability is demonstrated through an experimental characterization of turbulent boundary layer interactions with a steadily and unsteadily deforming elastic membrane.