aren't base plates and heat sinks the same thing?
you mount the laser modules to a base plate to remove the heat, I mount my laser modules to a big heat sink to remove the heat. same thing, just one has fins one doesn't.
indeed you really don't need to go down the tec route, fans are just fine.
look at the spec sheet for the diode you plan to use, for example 445. they can run at up to 60-70 degrees, so if you are running one at 20-25 degrees over driving a little wont be an issue.
im pretty sure reds also are happy to be ran at like 50 degrees.
the fans on my projectors don't come on till the base plate/heat sink reaches 25 degrees. once the base plate goes before 25 degrees the fans stay on for 2 mins then turn off. as I say I have no issues at all at keeping the base plate at 25 degrees
an yes heat sink which is my base plate is 300mm by 250mm by 40mm thick