Ok, first off, you are not allowed to use the word s.e.x on here. Bad word. You need to say same*gender*partner

Apart from that, there are two types of sponsorship applications for spouse, inland and outland.
With inland, you would both have to be in Canada, your partner should preferably stay in Canada during the duration of the processing which may take 1-2 years to get PR with but 5-6 months first stage approval and work permit if all goes well. The problem with inland is that if they want an interview because they are not convinced of your relationship or something else, they would send your file to your local office without the first stage approval and depending on their caseload, your partner could be waiting for them to have time for an interview for 1-3 years, stuck in Canada without a work permit.
With outland, your partner could be with you in Canada or could be in the US or could be travelling between the two on a regular basis, doesn't really matter. It would take about 7 weeks to approve you as a sponsor. Then the file is sent to the US for processing and takes another 4-9 months there, the average is 5. At that point, your partner would get PR, there is no work permit for outland. The downside is that if they want an interview, your partner would have to go to the US for it.
Bringing a truck full of stuff on a visit visa is normally not a good idea. Could you drive it across and say it's yours and your partner comes separately? A visit visa is normally good for 6 months, that is true. If you are still waiting after 5, you can apply for an extension. As for what your partner is doing in Canada while waiting, it's allowed to take courses of 6 months or shorter on a visit visa. Just an idea.