I can't picture what you are doing for an engine mount, but can you mount the engine while on the trailer in the parking lot before you approach the ramp?
You are going to want a ramp where there is a short pier or someplace to tie off briefly while you park the truck after launch. Mount the engine there and then head off?
No matter what you do, there is a certain amount of chaos in raising sails, tie off the halyards and clean up those lines, meanwhile the moment you begin that the wind will begin to act on whatever sail is up as it goes up. Move briskly with a standard routine. This is a light daysailer and will be more tender under your feet than you are used to. Now throw in wake from someone else leaving the ramp. You can do it in 60 seconds on a daysailer, with a routine, but it will feel much longer with the wind on the sails. Do yourself one favor: You must begin with the centerboard down and the boat pointing dead into the wind, and you must be sure step #1 is make sure the mainsheet is out and free so that if / when the boat itself begins to point a bit off the wind the sail doesn't fully fill, and instead continues to luff (flap) until you are seated and ready to trim it and sail off.
Your friend will show you all of that. See the routine once and it becomes obvious.
Do yourself a favor for the sake of the sanity risk you outline: the first time you do this without your friend, do it solo. No wife, no dog. Saving the marriage comes first.
Its easier from a slip. No truck and ramp complications and no ramp traffic. Take your time settling in with engine and whatnot, motor out to a quiet spot, point into the wind and raise the sail. No one behind you on the ramp impatient for you to get out of the way.