HD,
At 5500 wot rpm while 1 is up, OB is revving close to the min 5250 wot rpm range. If boating with more than one often, rpm will drop dramatically into the lugging red zone which is bad for the OB. In that case better go for one less (10) pitch OEM prop or repitch current 11 prop to 10, will pull wot rpm higher, will achieve better hole shot and transport more boaters, extra load when in need.
According to prop chart you should be running a 9.8 x 11 prop pitch instead than stated 9.9 x 11 prop, right ?
If OB sits at the sweet trasom height, trimed at 90?, as if having a fixed manual trim and propped right, should not have porposing issues, unless jon boats have rear hull issues that produces so.
Know is a PITA to dial sweet OB transom height while powered with a Tohatsu OB, but once matched along a prop maximation will be able to get the max out of that combo. Check prop shops in your location for rebuild or repitch.
Happy Boating