IMHO this is the one time I would use a shop that does a lot of RV's.
The base plate is not that easy to put on and hope you got it on correctly. A lot is riding on that base plate being installed correctly. Then you have to go out and buy the correct tow bar for it figure out the lighting/braking wiring for diodes etc.
When I first went to my local repair shop their eyes glazed over when I started talking- base plate - towing four down - RV!
So I took my toad to a dealership and they put it all on for me. Diodes for the lights, wiring, base plate, tow bar. It was ready to hook up to the MH when I picked it up.
For me it just seemed a whole lot easier and had piece of mind it was done correctly.
And I am REAL GLAD I did bring it there. The base plate the manual said my car needed did not fit.
When the service guys in the back got it they knew right away why it would not fit my toad and they ordered the correct one which actually was for another model 'because they had done so many of them'. Sometimes experiences trumps saving a few bucks on someone that does not have the experience of doing a lot of them.