I had a plaform installed for my 2001 Explorer 240 from swimplatforms.com last year. Looks great! I had it shipped directly to the marina where it was installed. They didn't have a template on file, so I had to make one for them.
No extra transom reinforcement was needed since the boat was designed with platforms in mind.
Monterey stopped making platforms for my boat a couple of years ago. They recommended swimplatforms.com.
I removed my extra platform ladder and ebayed it for $65.
One thing to consider if you potentially will be adding power trim tabs: give enough room for the trim tabs when attaching the platform support rods.