Can’t decide which vehicle would be best for my situation

I'd get a small fuel efficient car for daily driving (30k miles per year will eat up a vehicle quick).

How much over it the tahoe? If it's close, I might just live with it. If it's over by a lot, I would look at a 4door 1/2 ton.

Only if you are looking to move up to a larger trailer would I look at 3/4 or 1 ton. If you an find a good deal on a 1 ton, sure but lots more 3/4 ton available on the used market.

No, a diesel will never pay for itself only towing 3k miles per year.