Normal rule of thumb is to fit the maximum rated hp on the transom. That way you’re not wondering what if down the line? I had a check regards the Zodiac Pro 500 4.7m and it will take 70hp.
Yamaha’s 4-stroke 70hp is insanely quiet, frugal and light compared to competitors.
Anyway, put my wish list to one side. The 50hp will be fine, but as we say in Scotland it’s not going to set the heather alight. 1 to 2up will be fine. Add passengers and you’ll notice a difference.
You mention fishing. I’ve fished from my Ribcraft for the last 12 years and from a Zodiac Pro prior to that. The tubeset isn’t an issue. Be careful and you’ll be fine. Deck space and seating set-up however is an issue.
I’ve got jockeys. Great for rough weather and underway on route, but once you’re at rest, then they are remarkably uncomfortable. If the Pro has a rear bench seat, then that offers a degree of comfort. I’ve even deployed camp chairs on my boat for a decent seat, or even plumped for the Avon 8 tender (bagged up).
Launch and recovery should be fine if using slipways at tide. If you’re beach launching and miss the tide it’s hard work, especially if using ropes or manhandling a trailer, laden boat and fuel. Will be unbraked 750kg trailer. Keep on top of the bearings and trailer maintenance for a worry free life. LED lightboard should be top of your list.