Trying to figure out alternatives for remote accessory structure

[SplicedTurnip]

Hello, this is my first post here. I have a little experience with most types of household wiring through a decade of DIY remodeling, and building a new house but am not an electrician.

I'm researching options for getting power to a small cabin in the woods behind a house (Oregon, USA). It looks like the cabin is about 540 ft from the house service entrance/main panel (400 amp service 240V). Given the distance, I was considering a primary extension and a pad-mount transformer but the rough quote from the power company is looking like $16000 even if I install the conduit myself and has a long waiting list. So I'd like to look into cheaper options if they exist.

I would like to be able to have a 100amp or at least a 50amp sub-panel depending on cost. I was wondering about the possibility of running a 240V line 540ft from the service panel to a 25kVA or 15kVA transformer or other device at the cabin to convert the remaining voltage after voltage drop to 240V and 120V for use with appliances and tools.

Maybe something like one of these:

https://www.grainger.com/product/ACME-ELECTRIC-Single-Phase-Transformer-240V-4WUC4

I wanted to double check my electrical understanding and have a few questions:

• At peak loads, I'm understanding the transformer wont boost the voltage at the cabin back up to a full 240V and 120V. Ex at full load, if I lost 5% in the 540ft from the house panel and had only 228V coming into the cabin transformer, the cabin transformer would just output 228V and 114V for use up there, not 240V and 120V, correct?
• I'm understanding that sending the power 540ft by 240V to the transformer for final distribution to a subpannel with 240V and 120V circuits will cause less voltage drop and therefore require smaller wires than just running wire directly to the subpanel. Is this correct?
• If I did not have a transformer up top, any 120V circuit would require using 120V voltage to calculate the size for the entire length of the 540ft of buried wire but having a transformer would allow me to use 240V to calculate the 540 ft section's wire size, correct?
• Is there a better type of electrical device than a transformer that would help in this application? Found this thing but looks like I would probably need a transformer to use it and so probably not cost effective for what would be saved on wire costs: 20 kVA Single Phase Automatic Voltage Stabilizer - https://www.ato.com/20-kva-automatic-voltage-stabilizer
• For the application of having a 240V to 240V and 120V transformer up top, I'm understanding I would I only need two 540ft hots and a ground but no 540ft neutral before the cabin transformer since the two hots would act as eachother's neutral. But then the cabin transformer output would have two hots and a neutral. Is this correct?
• For the ground, I will have grounding rods out at the cabin. Would the post-transformer neutral and the ground in the cabin panel be bonded together in this application? If so, would the cabin's ground be isolated from the 540ft ground line to prevent the cabin's 120V circuits from energizing the 540ft ground?

Not sure if I did it right but from a basic online calculator set to max 5% voltage drop and cable prices online, I thrown together these four direct bury cable sizing and cost comparisons:

100amp panel, w/o transformer - 400 MCM Aluminum Solar PV Wire 2KV $5.18/ft > three wires 540 ft long (237lbs each), one 3/0 ground 540ft $3.02/ft = $10028

100amp panel, w/transformer - 4/0,4/0 & 2/0 Aluminum Triplex URD $5.39/ft 540ft long (382lbs)+ $2800 for 25kva transformer = $5710

50 amp panel w/o transformer - 4/0,4/0,4/0 & 2/0 Aluminum Quadruplex URD $8.50/ft 540 ft long (528lbs) = $4590

50 amp panel w/transformer - 1/0,1/0 & #2 Aluminum Triplex URD $3.16/ft 540 ft long + $2019 for 15kva transformer = $3725

Trenching and cable laying equipment not included

Do these estimates look somewhat realistic? I'm thinking to run my final ideas and hardware by an electrician but would greatly appreciate any feedback or redirection if I'm headed the wrong way or there is a smarter way. Sorry this is so long, feel free to only respond to part of it if it's too much. Thanks!