While I sympathize with the unpleasant time you had at the border, it seems that the issue was self-inflicted.
You're posting here so you have access to the Internet, the Canadian Border Services Agency has all the information you need regarding what is or is not allowed across the border. Similarly you can 'pre-clear' a person online to avoid the time & effort at the border.
As for your 5'er being a "secondary residence", the rules are almost the same in Canada & the US, if its parked on private property it could be (subject to certain conditions) a secondary residence, but when it's rolling down the road with a license on the back, it's a vehicle and no different than the truck pulling your 5'er.
I'm willing to bet the nice folks on the US side of the border would take issue with someone trying to enter the country with controlled drugs not prescribed to them and a prohibited weapon.