We installed Kato davits about 9 years ago. Kato's are rated at 350 each and have been fine. for our tender package. Our full tender package is the 9.5' AB RIB (150lb) a Yamaha 15 2 stroke at (79 lbs), 6 gallon fuel tank (45lbs) and misc stuff (oars, seat, junk) 20 lbs. Thats a total of almost 300 lbs. It's probably about the same as you would have with your larger engine.

Make good large backing plates out of 1/4" aluminum.

The most important thing is to make a ridged cross brace and secure the dingy very well.

We secure the dingy by 2 lines crossed from the tender to the big boat. If you have 4 lifting U-bolts you're half way there. ( 2 on each side of the inside front and 2 on each side of the stern)

What works well for us is to make one line out of lifeline wire with a hook on each end. The line should be just long enough to go from the outside u-bolt at one end of the tender to a point on the opposite davit near the inside. Make it short enough so you need to pull the boat a bit to hook it.

Make the second line different. We use a webbed ratchet strap with a hook on each end. Hook the second one to pull against the first one in the opposite direction and ratchet it tight. If you've done it correctly it pulls the tender toward the big boat and keeps it the entire system from flexing while sailing. ( looks like an X )

That's where the most stress is, when the boat tries to rip the davits off from the weight transfer at sea. A friend had his Simpson davits ( the big beautiful SS ones) rip right off while on passage.

There may be other ways to secure the tender but that method is fast, cheap and simple. One line pulls against the other and toward the big boat.

Tried to find a photo but who takes a photo of the dingy strapped to the davits.