Keeping in mind I'm no draftsperson; so these measurements are nowhere near precise; but hopefully this sorta kinda makes sense.
In my 550, no furnace, no TV, does have Air...
For the Upper cabinets, the ones on each side of the Air Conditioner, at the rear it's about 9 1/4" tall; and there is a bit of a slope up; so at the front it's 10 1/2" tall--however, there's a piece for the latch at the front. 14.5" deep, and 17 3/4" width. Both measured about that. That is interior space; remember the door (the teardrop shaped door) isn't that, it's about 14.5" wide by 8 1/4" tall at it's maximum width/height; but in the pictures online you'll see the door has that teardrop shape, so it's square peg/round hole type stuff if you are trying to put a cube in there (squishy objects work better IMO in upper cabinet--clothes, spare blanket)
The cabinets directly under, for me, since I have no TV it goes the full width of the camper: 58 1/2" interior width. At the back it's 7 1/4" tall, 10 1/4" deep. That entire space isn't 100% available for volume, though, there's a plug for the A/C, and the drain for the A/C takes some square inches on the right upper; also if you are looking for something that might be "exactly" 10 1/4" deep as container size, there are some footers (don't know if that is the right name for them) at the bottom; which take about 3/4" at the back and front, so if you wanted something to sit flush on the bottom, max depth I think you'd want something 9 1/2" to sit perfectly there. Again, that's interior space, the doors are 19" wide by 6 3/4" tall. But those doors are pretty rectangular; so if you wanted to put some rigid object in there, that's the dimensions that would fit without doing interesting angles.
For the cabinets under the teardrop windows (the Pillow side

), that arcs quite a bit, for me with no furnace, width is 43 or 44" wide, depending upon if you count the footer or not; 12 1/4" deep (if you don't count those footer pieces), and 11 1/2" tall at the front. That 11 1/2" tall remember arcs back; it's quite short at the back (maybe 2" ? before it starts to curve forward up to the max 11 1/2" tall at the front. Again: that's interior space. The doors are 18" wide by 10 3/4" tall. Oh, and same caveat for the depth; there's those footer pieces, about 3/4"--so if you want something to "exactly" sit perfectly flush, I'd call it 11.5" deep.
Remember... I'm not crafty in any way. I can't promise if I was off by 1" ... or 1/4"... I tried to err on "well, that looks like 10 3/4"... but I'll write down 10 1/2" "... so hopefully whatever you are looking for with these measurements will fit.
Also remember you'll have the under-the-mattress storage for those "don't need it quite that often" stuff. For me the 550; the one that doesn't hold the tire is about 18.5" x 15" , 5" deep.