Cooperative energy relaying helps in improving the radio frequency (RF) energy transfer (ET) efficiency by harvesting the otherwise dissipated energy and then transferring it to the nearby energy receiver. The achievable RF-ET gains are strongly influenced by the relative relay placement (RP), which may cause blocking of the direct energy transfer (DET) path between RF source and receiver, or energy signals from RF source and relay may add destructively. So, to maximize the utility of an RF energy harvesting (RF-EH) energy relay, we propose (a) a novel slotted harvest-then-transfer-energy protocol to avoid interference to DET, and (b) optimal no-impact on line-of-sight (Ni-LoS) RP model for avoiding obstruction to the existing LoS or DET path due to its physical presence. Further, an accurate piecewise linear approximation for harvested dc power as a function of received RF power is presented to incorporate the practical RF-EH hardware constraints. Since the optimal RP problem for maximizing harvested energy at receiver from EH relay is nonconvex, conditional generalized convexity principles are used to obtain the closed-form global-optimal solution. Numerical performance of the proposed utility maximization models for EH RP is investigated under practical RF-EH system settings.