I really don't think a temperature check is that important. As long as you get it up to operating temp, not just the coolant, but the ATF, then I think that 80° is what operating temperature is. Your 30 miles might be enough. I usually try to check mine after a much longer drive if I remember. Someone also mentioned that there was a bulletin out to ignore the low temperature mark and only use the 80° mark.

__________________
Len
'59 220S Cabriolet-SOLD and living happily in Malta
'83 240D 351,500 miles original owner-SOLD
'88 560SL 41,000 miles - totaled and parted out
https://sites.google.com/site/mercedesstuff/home
'99 E300 turbo 227,500 miles
'03 SLK320 40,000 miles - gave to my daughter
'14 Smart electric coupe 28,500 miles
'14 Smart electric cabriolet 28,500 miles
'15 Smart electric coupe 28,000 miles