In this poster presentation we present an extension of Feynman's variational path-integral approach to include two-phonon processes beyond the Fröhlich model, which have recently been shown to be of importance for the description of the Bose polaron. We obtain significant corrections to the ground-state properties of the Fröhlich model at strong coupling and compare our results to other approaches in the literature. One advantage of this approach is that it can be used at finite temperatures and in addition allows for extensions towards the treatment of multiple impurities. Our results provide an indication that the effective mass of the Bose polaron is particularly sensitive to finite temperature effects, which can be of relevance for future experiments.