Sorry Christian, didn't notice the thread...
Keel guides are a must, or at least, if you can fashion something that'll steer the keel to the center of the trailer. PVC pipe works, we're talking very small amounts of pressure to steer the boat to center.
Also, that's a decent fin keel size, so the trailer will need to be in deep. HOW DEEP is obvious, but how STEEP your ramp is dictates how badly you need a bow support. You see the boat floats flat, but the trailer is in the water at an angle.. and even if you get the bow to float up to the winch, its angle will go up dramatically as you pull the boat out (rock back)... so a Better way is to put a bow roller on a support, and winch the boat UP the roller and out of the water as you pull forward (you'll still get rock back, but it shouldn't be as bad)... the advantage of this is that the trailer need not be as deep either... because you are actually pulling at least just the bow out of the water some (and up)...
Picture of what I mean:
Boat looks good, spin(s) look good. Not sure I agree with the ditching of the fossil fuel burner, but to each his own. You'll have to pry my 2 stroke motor from my cold dead hands. I'm loving my 7.5hp yacthwin... its quiet, runs well, has lots of power, an alternator, and has very few issues. Loved my Johnson 3.5hp too, was light (35lbs), and had everything in 1 package... plus pushed my Capri 25 to hull speed. NO wires, no fuel lines... just drop it on the motor mount pull and go (1 tank of gas gave me 45 minutes WOT, half throttle was like an hour and a half!).
Strap launching will likely be needed if your ramp isn't real steep (likely)... Do you know if you have nice tongue weight on the trailer with the boat on? If you do, then you SHOULD be able to strap launch/retrieve without having to put rear trailer dollies on. Otherwise get a rotate to lock down trailer dolly rated to like #1500... and place it dead center on the last cross member of the trailer. Keep it about 2-4" above the ground (you really don't want to use it unless you have to)... it'll keep the trailer from flipping up as soon as you try to pull the boat out.
Back the trailer down to about 3 feet from the edge of the water... make sure your truck/trailer are already perfectly aligned with the ramp.
Wheel chock the trailer.
Keep safety chains ON the trailer.
Unhitch, to a heavy duty dolly, preferred a large wheel front landing gear type dual wheel dolly if you can find one.
run your come-along/tow strap from your safety chain attachment point to a secure spot on the trailer (prefer low), and back. I used a
10,000lb rated tow strap (25 feet, and ran from hitch, to winch post to hitch).
Undo your safety chains (secure them out of the way).
Pull truck forward 6-12"
remove wheel chocks..
Lower rear dolly if you need it (again 2-4" off ground)
back trailer down.
get your boat on, use the bow roller/winch to lift the bow UP to the winch, bow ideally will be out of the water 2-4"
SLOWLY pull the boat/trailer out, check to make sure the keel is centered... you likely will have a small range of float where you can push the stern of the boat around, to align the boat to the trailer, its also usually where you CANNOT see the keel.
Reverse above process and hitch back up.
If push comes to shove, and the boat is on, but not entirely forward on the trailer (it happens believe me, and you'll know this by seeing the trailer resting on the aft dolly). You might need drop back, and work the boat forward.
If you get the boat ON the trailer, and mostly centered, and hitched up, but its still not all the way forward... 10 guys/gals can LIFT the boat up, while an 11th can winch the boat forward, and you'll get it where it needs to be... ASK ME HOW I KNOW!
Good luck. Shame you aren't closer man... I'd be happy to help in the train wreck