Welcome to my world! The best, and in some cases only, solutions often come with a high price tag. Many plastic linings have been used successfully for concentrated HF but in your case the high temperature is an issue. The upper temperature limit is often determined not by diffusion of HF nor the chemical and thermal stability of the polymer, but by the complex stress patterns that develop during lining and in service as a result of the large difference in thermal expansion between the plastic lining and the shell. For glass-backed or polyester backed resins used in lining carbon steel vessels, the suggested temperature limit is 60 degrees C for FEP, PFA, ECTFE, and PVDF. For HF concentrations higher than 48%, the temperature limit is even lower. Bonded and baked linings have been used with some success but due to the aforementioned thermal expansion issues such linings are not recommended above 80 degrees C. You might want to try contacting an HF manufacturer for some MOC suggestions. Good luck finding an appropriate material of construction at a cost you can afford.