Great question. My advice would be to do a combined procedure. Have a tummy tuck performed by your plastic surgeon at the same time as the performance of a laparoscopic repair of your hiatal hernia by a general surgeon.
Most hiatal hernias can be managed with medication to reduce the acid formation. Hiatal hernias can also be fixed with laparoscopic minimally invasive surgery. if it turns out that your hernia can be fixed in this manner you could get your tummy tuck at the same time. This would allow you to have just one recovery and enable your tummy muscles to be tightened with affecting your hernia.