I had a 2007 Gulfstream for 10 years with twin F200's. It's a great boat. I slept overnight, took it to the Keys twice a year from Ft Myers, FL (180-185 miles) and trailered it everywhere. Loved it.
1.) I would NOT have that boat with a single engine. It planes much easier with twins, there's better control in rough seas and it's 10 times easier to horse around a dock that a single equipped boat would be. It is a widebody as mentioned, and I think it's too much boat for a single, although many have them.
2.) You can sleep two below in the V-berth, if you are on good terms. The fold-out bunk above is OK for kids or a small adult, but it's far from ideal. Basically, the boats sleeps two. Stove and sink to port are useless; I put overnight bags on them....
3.) I prefer 200's over 150's but 150's would be better than any single. Mileage is about the same, with the 150's maybe a tick better.
Cruise Numbers Below with F200's.
3600RPM 28MPH 1.9-2.0 MPG.
3900RPM 31MPH 1.9 MPG
4400 RPM 36MPH 1.7 MPG (Hi Cruise.)
These numbers are with bottom paint. My son now has the boat-he stripped the bottom paint off and his numbers went up 1-2 MPH per RPM setting and he hits 2.2 MPG on calm days.
4.) Trailering is no prob if you have a strong rig to pull it. I recommend diesel with at least a 3/4 ton truck. My 232 weighed in at 10,100 lbs, loaded for Bear with full fuel. Yours will probably be less. As Stang mentioned, permits are required; Anything over 8' 6" requires special permits to tow legally. Some get them, some don't. Captain's Call here.
That's about it; It is a really big 23 footer and will take reasonable seas. Anything over a two foot wind-driven chop is uncomfortable in one, but not unsafe. Open ocean long period swell? Dunno...I don't run the oceans.
I say get it if the boat checks out. Stang also mentioned the corrosion issues. My F200's had it, many 225's did, as we all know. Stay after that. Good Luck!