Will a Tummy Tuck Help with Hernia Repair?

From you description of multiple recurrent abdominal hernias and being 50 lbs overweight, weight loss is probably the surest way to increase your chances of success with another hernia repair operation.
As previously mentioned, complex hernia repairs do benefit from collaboration with a plastic surgeon that has expertise in these procedures. In your case, an abdominal wall reconstructive procedure may be needed. Complex procedures such as "Component Separation" and reconstruction of the abdominal wall are performed by a subset of plastic surgeons.
A significant focus of my practice is performing plastic surgery on patients that have lost "massive" amounts of weight--often 70 to 100 lbs or more. Some of these patients have had recurrent and multiple hernias, and in no case have I had to resort to using mesh or a complex abdominal wall reconstructive procedure.
For a significantly overweight patient, weight loss leads to loss of intra-abdominal fat, which "loosens" the abdominal wall. The net result is that hernia repair becomes much simpler after weight loss, and therefore the anticipated rate of hernia recurrence decreases significantly as well.
Here is an example of a patient that had multiple large and recurrent abdominal hernias. She is a 52 yo that previously was 100 lbs overweight. She underwent a gastric bypass procedure and presented a normal weight, but with significant excess skin and laxity of her tissus. All of her hernia were repaired easily without mesh, and we were simultaneously able to get significant body contour improvements by performing a lower body lift.

Without weight loss it is likely that your 4th surgery will undoubtedly result in a 5th surgery. I agree that you would, at this point most likely benefit from a "separation of parts" repair of your anterior abdominal wall. Understand that this is pulling out all the stops to repair your hernia and could result in a final cure to your problem but why would you jeopardize this by remaining at your current weight which is the most probable cause of your previous herniorrahphy failures?

It is likely that a tummy tuck would be very helpful for your problem.
However, the complexity and risk of your surgery is relatively high. It will likely be necessary to go into the abdomen, which has a unique set of risks.
Complex hernia surgeries are best accomplished with a combination of a general surgeon and a plastic surgeon, each using their unique expertise.
Also, surgery such as this should generally be performed in a hospital setting.
It is also best to be at an ideal weight, if at all possible, before proceeding.