Mefo Explorers 2-up on tarmac? Advice please.
 

Need opinion of experienced travellers.
This year for first time I am taking my wife with me to go to Norway.
And this year I am doing it on Dual Sport bike - DR800.

At this moment it has set of almost new Mefo Explorers 99. Being road rider for 15 years I have zero to none experience on tires like that - I used to ride fast bikes with wide road tires. I used them really offorad and it was OK.
Now I am concerned about safety (I like my wife! :)) with Explorers. I do not really need offroad tires for that trip, but then I do not really need road tires on DR after that trip. So - to change or not?
I am not 100% sure that braking will be adequate on Mefos on 185 kg dry weight bike + about 20 kg luggage + my 85 kg + my wife's 46 kg. At least on wet tarmac they did not inspire confidence in me when I used front brakes, but then it was when I was tired after day of offroad riding, so my "senses" were blurred :)
Anybody has any experience with it? Any advice? Pleease!