There are others who can address this but here is my interpretation of where your headed based on my lengthy dealings with MTO and OPP:-
1 "Farm vehicle", in Ontario they are not registered. They carry a slow moving vehicle sign which is indicative of traveling at less than 40 kmh. Insurance is through the "property" or "farm" as part of Liability. To be viewed as an "Implement of husbandry" (highway traffic act wordage) there has to be a connection to the land. See notes below
2 To register it for the road is sketchy, I am not going to counsel you to break the law but all I will say is that it is a partial track laying vehicle for which there is a weight limit (IIRC around a ton and a half). There is no split between steel or rubber track. Whether you put your cards all on the table when you register things is up to you. Some clots will say "I have a big heavy ex army tank like thingy and I want to register it" others will say " i would like to register my "1945 White truck" and cut it short there. Can you see the difference?
3 If you talk to Lant Insurance and speak in soft dulcit tones you may well get insured.
Notes:-
A half track was made for road usage with lighting etc fully compliant at the time of manufacture.
Rubber tracks could be mistaken for rubber wheels
"Implement of Husbandry", we have 2 Kawasaki Mules and are a registered and legitimate farm carrying out farming, tractors, crops etc etc. If we take the mule on the road we are illegal with SMV sign and no ATV plate. Mule must be plated as ATV and insured to be on the road. To cross the road (we have farm land split by public highway) we must comply as stated and wear helmets and wear seatbealts as fitted. If not, shut it off and push it across the road.
The mule may not travel down the side of the highway even if the municipality allows ATVs to do so because it is NOT an atv under HTA as the definition is "to sit atride the machine".
We have decided not to go toe to toe with MTO and OPP even though loaded with baler twine and tools we do "get around" but do so by coating it with invisibilium . . .
Feel free to ask more questions but remember we are in the public domain and others may be reading what you write.
I am well up for any debate on MTO related issues anytime
R