If you're trailering a boat, just leave the motor on (secured in the down
position if safe to do so), tanks secured in the boat.  That's how most
folks here do it.  There's no way I'd have it in the van.

I've gotten pretty good at servicing the collection of outboards owned by
friends and family.  Dennis H is correct in that the two strokes are much
simpler...they're pretty much carbureter(s), reed valves, and an ignition
pack.  If the lower end is serviced yearly, and proper oil mix etc
maintained, they can last a very long time.

However, they suck gas, are pretty gross polluters, are louder, and you
always need to mix the gas if they're not oil injected.  The fact that you
have twice as many power strokes over a 4 stroke does make them
lighter..but at the cost above.  Obviously a four stroke is much
cleaner/efficient in that the intake and exhaust charges are kept fairly
disparate.  It also has the advantage of a sealed crank case and a pressure
fed oiling system.  Either motor's achilles heal reamains the rubber
impeller water pump in the lower end.  Considering David Suzuki's views on
the planet, current fuel prices etc...the four stroke's my vote.  Truth be
told, I'm an even bigger fan of sail power :-)