Would a sliding genioplasty be enough to tighten up & give a V like jawline? Or should I be considering V-line surgery? (Photo)

A sliding genioplasty is the correct chin procedure for you which is really just the front part of v-line surgery. You do not need to have the posterior part of v-line surgery done. The sliding genioplasty could be combined with perioral/jowl lipsuction to ensure the lower facial fullness is resolved. While any form of chin augmentation usually makes the nose look smaller, that bears investigation by computer imaging so you can see the effects of a sliding genioplasty alone as well as combined with a rhinoplasty.

Thank you for your photos and question. Based on the pictures, I agree with your assessment of your chin and soft tissue. Custom implants can reliably augment the skeletal deficiencies and give you more facial balance and harmony. I recommend a consultation with a board certified plastic surgeon who is experienced with craniofacial surgery and implants. 

You have a vertical facial growth pattern with a high slope to the lower jaw and a lack of projection of the jaw and chin. A geniopkasty and jawline contour definition will achieve much of what you noted.. the nose will look more balanced once the chin is projected and can be reviewed at that time.