Hello,
My g/f and I are planning to ride from NJ and spend about a week riding in Montana and Wyoming. Trip will start on Friday and we hope to go through Beartooth hwy, 296, Going to the Sun, Triangle loop, Hot Springs, Glacier road, Flaming George,  Devil's Tower, Yellowstone, Tetons etc... All the individual trips are already pre-planned in Base Camp and loaded into Garmin but we are not sure about the timing and because of that do not make any hotel reservations.
Would you please share your experience on how hard it is to find a place to stay every night in that area? Luggage space is extremely limited and though we aren't the newbies in long distance motorcycle traveling I am still in doubts whether I should take a tent and sleeping bags into this trip... Please share your thoughts, we appreciate any input. Thank you. 
 

I actually have two friends that are doing this ride as we speak.  Left KC and riding thru MT, WY on the way to Banff NP.  Coming back thru WA, OR and Cali.  I'll drop them a text and see what accommodations are like.

Well, you've already started, so this is too late but I just did practically the same trip.

You're going to a National Park area in peak season so rooms are tough to come by and can be very expensive. I would recommend sticking to a tighter schedule and reserving rooms in advance. I normally just roll but the combination of NP's and high season means a poor planner might sleep by the side of the road.  I don't camp.

Jackson is high priced but super cool in a touristy way, anything near Yellowstone is high but there are some bargains to be found.  Avoid the Rodeway Inn in Livingston MT, $160 a night for what you get is ridiculous, just robbery.  Much closer to Yellowstone is Gardiner MT, just outside the north entrance. We stayed at the Yellowstone River Inn (in the 'new building') and I can't recommend it enough.  Nice lady that runs the place and the maid is a smokin hot Czech girl named Magda who is lovely and just as nice as a human being can be. Ridiculous view out the back over the river.

We stayed in Kalispell the night before we did Glacier at the Econolodge, which is was reasonable and nice.  Right on the main drag, tons of places to eat, gas up, buy stuff etc.  There are places that are closer up the road in Columbia Falls and West Glacier, they may be more, I know nothing of them.  The Econolodge was perfect.

We also spent a lot of time in Idaho, which I can't recommend highly enough, the path we took anyway.  We went from Gardiner MT to Stanley ID in one day.  Fantastic roads, Stanley is lovely. Next night was Kamiah, great roads to there also and we ate downtown in the old bank, stayed at the Clearwater. Next day was Lolo Pass (fantastic!!) to Kalispell. Of course, Glacier is stunning.

One suggestion would be to try to stay at hotels in ski areas. They generally require more capacity in the winter and so have a little more inventory in the summer. Prices are generally not cheap but way less then the winter prices.