From the frontal photo alone I cannot tell reliably about how much skin excess you have, but I think there is enough for a TT. A side view would help, but the real answer will come in the setting of an in person consultation.
I am not sure what your definition of pelvic instability is, but it is also always an error to think that a tummy tuck will do anything for functional problems. It is an aesthetic procedure.
Thanks for your question,and for the posted photo. When you are ready for an in person consultation, RealSelf has listings of surgeons in your area. You should consider cross referencing the listings from the The American Society of Plastic Surgeons (plasticsurgery dot org). A listing in the ASPS website assures you that your surgeon is not only board certified, but also is a member in good standing of the major plastic surgery organization in the U. S. Thank you for your question, best wishes.