Hello Canadian drivers! I need some help from you guys!

I am thinking on buying a rv, This is the first time I will buy a car and I need your help.
I'm looking for a 22 to 28ft motorhome class c, the ones that fit my budget (~$5000) are from the 80's,
so you guys have more experience when buying cars, what do you recomend to look for when inspecting the rv? mostly regarding mechanical stuff...
some rvs from the mid 80's have 60k-80k km is that possible?
how can I know if they have messed with the odometer?
Also, what is the average kilometrage when a truck engine (gas) needs repairs?
When I buy it do I need to get insurance for a whole year? if so, around how much? just a rough number to have an idea on what I am getting in

I am not going to move the vehicle much... I am just looking for a home that's not expensive while I finish with my studies. probably take it on a trip somewhere these comming summer buts thats it.
Thanks a lot for your help guys!