Arctic circle to the Pamirs, Tarp or Tent??

[holodragon]

Hi all
I am leaving the UK to travel up to the Arctic circle & on to the Pamirs.
My route is Norway, Finland, Russia (Karelia, North of Moscow, Urals, Tomsk), Kazakhstan, Kyrgyzstan, Tajikistan, Uzbekistan, back into Kazakhstan & round the top of the Caspian sea, Volga Russia, Georgia, Armenia, Turkey, Bulgaria & back to the UK.
I am leaving at the end of May & should be back about early October.
Do I take a tarp (ex army camo) & bivvy bag or tent (Vango Halo 200)????
The tent is free standing with a reasonably small footprint & is plenty big enough for myself & all my kit if necessary. The tarp can be tied to the bike or I can use a tarp pole in the absence of anything else to attach it to.
The tarp including a tarp pole/para cord/mozzie net/bivvy bag/pegs weighs 2.7kg & packs down to 2/3 of the size of the tent which weighs 3.6kg including pegs. I would save weight & space with the tarp but is it going to be enough protection in the areas through which I will be travelling?????
Thoughts please,