Tummy Tuck Surgery and Hip-to-hip Scar my Only Option?

There are 3 things that a tummy tuck does that you cannot accomplish on your own with diet and exercise alone: tighten skin, repair muscle separation, and remove localized fat if needed. If you do not have a muscle separation(diastasis) then your recovery will be much quicker. There are no short-cuts for skin tightening however, and from what you describe it seems unlikely that anything short of a full tummy tuck will do. You should see a plsatic surgeon for a personal consultation about whether the muscle repair is needed and whether it affects cost.

In general, the more skin removed, the longer the scar.  Quality and placement of scar more important than length.  Yes, less expensive without muscle plication, but after five term pregnancies, if you're flat now, plication will supercharge you.  Anyone who is opening you up for tummy tuck should want to make you as sexy, youthful, curvaceous, and beautiful as possible, and thus should not want to do tummy tuck without plication.