So the 1st time we ran the boat before I bought it they screwed the hose into the flush connection and turned it on, H20 started flowing out of the pickup on the stern, I asked the owner if we should shut isolation valve and he said it didnt have them.... I thought that to be odd... So now that I'm looking at this setup I think it's even more strange not to have an isolation valve between the water pickup and the strainer. Please tell me my concerns are warrented... How the hell would you open up the strainer to clean it out w/out an isolation valve?

On the trailer.....you need to put some valves on it.

Is the top of the strainer above the water line?

No, their in the bottom of the bilge aft of the stepped bulkhead. Undoubtedly they have head psi on them...

my valves are near the transom where the water intakes are. there is a metal rod attached to each that is mounted by the hatch arm. pull or push that rod to open/close. its a pita.

Are there any shutoff valves? If for no other reason, I'd still want them right after the intakes to shut off water in case of a leak.

Yeah, no shutoffs. They wont be bad to plumb; just wanted to if anybody else thought it was strange.. I guess I'll get on it!

I've got one right at the pickup that is a little awkward to reach but cuts the water off to everything, then one right at the strainer that is easy to reach for flushing or cleaning the strainer.

I have a SS valve before the strainer so that when we overnight I can flush the motors and keep salt out. I've never had reason to clean the strainers in the water (or really at all for that matter) but I guess that would obviously depend on your boating conditions

What happens if a hose pops off, bursts, etc? The boat will be at the bottom of the lake .
I have shut off valves screwed directly to the pickup, no hoses inbetween. Used for emergencies only.