Outboard on a Catalina 27

[new-to-sailing]

Hello everyone, I am planning to add an outboard to my Catalina 27, it will likely be a short term situation (1-2 years) so thinking about how I could reuse the outboard I buy for a dinghy down the line. A few questions related to my plan below.

1. I am planning to buy a 5hp Tohatsu Propane, I believe this should give me the power I need. I will only need this for getting in and out of my slip and the occasional longer trip which would only be in calm conditions. I have seen some who say this is fine, others suggest going for more HP, anyone have thoughts on this? Or better yet is there any sort of calculation that can be done given hull etc. to see how this will fare.

2. Most people use a 20” or longer shaft it appears for this type of application, if I install a bracket that allows the prop on a 15” to be installed as intended is there any other reason I should use a long shaft? A big reason I want to use the 15” shaft is to make this outboard more usable for a dinghy down the line.

3. Any recommendations for outboard dealers in the Chicago area? Or recommendations for adjustable outboard brackets?

I know there is a lot on here and certainly a well discussed topic but any thoughts or other resources on this would be great! Happy to clarify if needed.