sir agar ap karachi to mithi via thatta and badin aty ho to till badin aap ko cng mil jae ga. after badin 3 option hain you may go direct mithi, or go to naukot than mithi (about 20 km ziada ho jaen ge) third option badin to tandobago (last town where cng available) than jhudo than naukot than mithi.
agar aap via hyderabad aty hain to rasty me mirpurkhas ae ga again 2 options from mpk--> go through umerkot (umerkot fort is famous also) than islamkot mithi not comes through this rout and 2nd option mpk ---> digri, jhudo, nkt, mithi, islamkot, nagarparkar.
petrol available in every town and city, optional in nagarparkar but i think there is a petrol pump there also.
best plan suggested by me: karachi-> gharo (water park is option) --> thatta (makli hills, kenjhar jhel on hyd road, shahjhan masjid) --> badin (cng last point) --> small towns --> after vango mor you have two options mithi direct or naukot i suggest go through nkt (nkt fort) --> mithi (night stay at mithi) visiting points asia,s largest ro plant on way, gadi bhit is famous and temples (hindu comunity is more in these areas) nothing special you should visit all within few hrs --->go to islamkot ( road condition better but few km before isk road is not carpeted and repairing continue, (in islamkot sant nenuram ashram is famous and nothing special) take mineral water and ready food items chips, biscuits etc with you bc from now aap ko aagy quality food ya water mushkil se mily ga, haan choti choti jhopra hotel mil jaen ge but food quality so so mily ge to agar compromise karty ho to chaly ga. acha rhy ga agar yahan se petrol tank full karwalo. from islamkot to nagar road condition is not bad but be care full of animals and kids bc small kids suddenly comes out from green trees and you are not able to control the car, godi mandir is on way, than famous MARVI JO GOTH and well where she take water and kidnapped by king soomro of amarkot, than verawah.. here rangers check post (1 st one is at islamkot) here you may show you identity may check your car diggy and take your cameras (mobile phone allowed some times but with low quality camera you may request them to take mobiles but cameras mostly not allowed and they give you receipt if they take your cam. direct go to nagarparkar no need to enter in verawh town (here only famous mava available in verawah so if you like mava than go to town than came back on your way) before nagarparkar Bhodiser talau and bhodiser masjid are very famous you can see those before entering nagarparkar. here again a check post you should introduce your self and give identity. karonjhar jabal is famous it is oval shaped and here few natural and men made dams (small) also godhro nadi which only shown during rainy season, sardhro mandir from nagar ( half by zig zag hilly road and half by walking but very adventurous you may hire a local person (kolhi) as a guide and takes your water and food items also. from nagar you have options to go further by 4x4 taxi hiring from nagar for kasbo villiage and chorio villiage (choorio is last village than pak-ind border seen from chorio you may not allowed to go further, in choorio only an old temple and border to see but i think you like that. stay at nagar for 1 day to enjoy the whole area other wise only nagarparkar is day trip only. for camping i give you a tip that in talluqa hospital nagarparkar there is much space and no fear of snakes if you have tents than no issue but need permission of MS hospital which is not so difficult if you have some gutts 
otherwise jhopra hotels are also available and guest houses also but you may book early.
from back nagar parkar --> islamkot --> go through umerkot (Amarkot) road on way you may go to dargah saed Mean shah --> on way ragers checkpoint near chor left turn to umarkot --> small villiages in bw --> umerkot fort and temples--> go to mirpurkhas--> hyderabad--> karachi.
things you have:
emergency lights + torch
tent (rain coats optional)
ready foods or cocking arrangements ( for tea,coffee and foods)
first aid box
mobile phone with camera (optional)
clean or mineral water (available everywhere till islamkot also in nagar but short in rush days)
you are almost near small cities or towns so every necessary thing of life available easily. warm area but cloudy now a days to garmi nahe lagti haan pasina buht ata hai
kuch aur pochna chahen to welcome..
