With a trailer that long, your selection of campsites will be restricted. The best you can do right now, is begin searching State Park web sites, National Park web sites, and go through the steps to reserve a site. Most sites will want you to put in your length and then only available sites within that length or longer will return as available. You don't have to continue with the reservation, just cancel it then and try another park.
Yes, it's a little time consuming, but you will readily see what's available for your length. You can begin to build a list of parks that will accommodate your length. You may want to boom-dock. There again, do some research right now on those spots and places you are considering. Look at Google Map Sat elite views too and compare all this information together.
Considering you are on your 3rd camper, you are not a "greenie" to this life style. You know how to look these things up, research camp sites, and then you can evaluate your own opinion if you REALLY want to go with a camper this long. Only you can decide that.
That's my suggestion, do the research now, before you purchase.
The biggest draw-back I see with a trailer of that length will be your tow vehicle. Yes, you'll need to step up to a semi-truck style tow vehicle. You may also need to get a CDL endorsement on your drivers license as this size of truck is usually used for commercial purposes. This will depend upon your State of residence.
Another thing you need to consider IS the total length. You need to check with the laws in your state how long you can go with a combined vehicle length. Every state has a different limit requirement, but the only one that matters is your own. Other states will not question your length if you are longer than their state requirements. It only matters in the state you license your vehicles and your drivers license. Follow the rules of your state and stay legal.
One more thing you should consider? These longer trailers are designed more for commercial purposes. What kind of electric supply is required? Are they 50 amp, or do they require something even more? I don't know. But something you need to consider.
If you are in a "normal" State Park, lets say, you may only be able to plug into a 30 amp power source. If the entire rig requires 100 amp, well... you'll have to figure that out. So, double check the power requirements for this trailer. I'm just suggesting something you need to consider. It might all be OK with 50 amp, but I don't know. You do need to know before you buy.
And .... where do you store the camper of that length when you are NOT camping? If you have your own property that allows RV parking and you have the space, no problem. But if you don't have the space for something of this length, or you live in town with zoning restrictions, you'll need to consider the cost. You currently have a 5er, so you probably have this already figured out, but still.... the extra length gives you something to think about.
Edit: I see you are from Canada.... still the same... check the driving / license / legal length limit / etc. with your local jurisdiction.
