I've wrestled with similar issues in several states. Not CT. Some states have nice provisions for getting it done, others don't let reality interfere with their process.
No seller in his right mind will cover you beyond where you take possession, and even if you think they are they probably aren't, or aren't good for it.
The nut roll some states want you to go through, if you want to do it with the i's dotted and the t's crossed, typically means you wind up doing some sort of temporary registration to get the thing legal to the point where you drive it around to finish the real registration. Extra cost, hassle, and process.
The alternatives are basically trailer it through the process so it's never driven until you get it all done, or drive it before you dot every i and cross every t.
Player's choice. If you decide to cut a corner, note you can probably insure the bike before you register it. So if you are driving it to get it registered, you might be guilty of no registration but at least you're not uninsured.
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