I couldn't find time to read your full program. I did a road trip in February 2016 from Islamabad to Karachi and back and plan for Gwadar in coming winter. I shall share with you what I know. But sorry, not now, sometimes in future. At this point, I can only say that your program is feasible.
Today;26-10-2018, I am again on your post,
In my view Corolla GLI -2016 has reasonable ground clearance for this trip.
I suggest you take different route while traveling through interior Sindh, first while going and the other while coming, like I did. On one side, use National Highway instead of Super Highway and you can cover a. Kot Diji Fort and nearby 6000 old ruins near Khairpur, b, Keenjhar Lake, c.Thatha and Shah Jahani Mosque, d. Makli Graveyard, e. Deebal/Bhanbhore ruins near Gharo creek; while on other side you can take Dadu-Larkana road and cover a. Manchar Lake (disappointing), b. Lal Shabaz at Sehwan, c. Mohenjo-Daro, d. Garhi Khuda Bux.
Except for big cities like Sukkar, Khairpur, Nawab Shah, there is no reasonable place for night stay in interior Sindh.
Now about your program:
Day 1 - A day before we will reach Lahore for some family event and then next day start early from Lahore and reach Bahawalpur by mid day and cover Gulzar palace, Darbar palace and noor mahal. Reach Sadiqabad for night stay.
Day 2 - Explore Rohri Sukkur area: Sukkur Barrage, Lansdowne bridge, Lab e Mehran, then drive towards Larkana and visit Garhi Khuda Baksh. Visit Mohenjodaro if time permits and night stay somewhere between Larkana and Dadu according to situation.
(Seems reasonable except that Mohenjo-daro is a must. Never skip that. Try to reach there before 4 pm otherwise museum will be closed. 2nd, there is no decent place for night stay between Larkana and Dadu,)
Day 3 - Visit Sehwan and Manchar jheel on the way and reach Khi and night stay there.
(Be prepared for disappointment at Manchar Lake. We couldn't find a proper place even to stand alongside the lake)
Day 4 - Khi to Kund malir beach and few stops at Gadani ship breaking yard, mud volcanoes and night stay there.
(To my knowledge, one can reach Gwader from Karachi in 8-10 hours only if he doen't use time in visiting places on the way. Please do time calculation of this leg of journey, as accurate as possible: Because, again, there is no decent place for night stay between Karachi and Gwader, except the naval base Ormara (need a naval reference to stay there)
Above is only my viewpoint and you should verify by other means as well