I wish I could get the motor mount installed right from the beginning, but the dealer was right away trying to convince me I don't need one, so I quit asking.
Don't ask him. Tell him. Does he not want your business? The Cheeta mount is pretty much the only one out there. Check my posts, I have some advice about them.
I've had a number of day sailers over the years. Having a Torqeedo outboard motor on my Getaway is the best move I've ever made. I can launch from any ramp, no matter the wind direction or how bad the ramp is for sailboats. I don't have to worry about whether it's an unfavorable channel. If the wind dies, or gets crazy high, I can strike the sails and motor back in.
I got the whole enchilada when I bought my boat too. The spinnaker is a lot of fun, but it's a light wind sail, don't try it in any high winds or you'll shred it.
Don't skimp on the trailer. I had a Hobie 17 with a cheap trailer. It broke, actually broke. The difference between a good trailer and a cheap one isn't that much, and it makes a heck of a difference in the long run. That said, double check everything the first few times out. I have a galvanized Genesis trailer. Good trailer. But with about 150 miles on it, I found a spring shackle bolt backed almost completely out. That was supposedly held on with a lock nut. The only way I can see that happened is if the nut wasn't installed by the factory or dealer, whoever assembled the axle. If the bolt had fallen out when I was towing the trailer, the axle would have been ripped off and undoubtedly destroyed the trailer, boat and possibly me!