Fuel Efficient Trawler and Electronics

[Cruising Roo]

Hi all. Very new and just doing my “due diligence” of living aboard a motor boat. I am from the south of Australia. To that end, may I ask you experience sailors the following;
1. What is a fuel efficient trawler hopefully not much more than 45 foot, and
2. Are the trawlers the most efficient option. I certainly am not in any hurry
3. Are single engine boats more efficient and is there anything I should be aware of in this regard
Let me throw in another question if I can. My plan is to stay in Australian waters and frankly see no need to be too far off the coast so what would be the minimum electronics. Is a radar that important. I had a small boat with radar which was good for steaming at night but I am planning to only steam in daylight hours. Thank all
Darren