Welcome to RIBnet Briantroy,
If you're not bothered by stinking insurance then your plan sounds fine to me. I have a similar sized inflatable (non GRP) and a 10hp.
As you say, reckless abuse of power is the concern here so take it easy until you get the hang of it - that thing will go like a scalded cat and certainly could throw you out. Getting your very many rocks forward will help when getting underway. Get a tiller (steering bar) extension like this:
About two feet is fine, telescopic is best as you will want to reduce it for better control when going slowly. You can make one up out of PVC plumbing pipe to see if it suits you first - just make sure it's well attached!
The other thing - make ABSOLUTELY SURE that you wear a killcord at all times when underway. It's the best stinking insurance policy you'll ever have.