Installing a winch and battery box is no more difficult than changing a tire. But then again, I know people that call AAA to change a tire. In fact, I know a guy that actually takes his boat in to a detail shop to have it waxed for him.
Bottom line is that anybody can do anything if they try. OTOH, some people don't have enough confidence to try. If you don't have the time or confidence, but you have plenty of money, hire somebody. Personally, I won't let anybody touch my boat because I've had too many cases of having to fix somebody else's repair.
Now, if your question is regarding the job itself. I have issues. My electric winch setup was fitted with QD bolts. After launching the winch went in the trunk of the car. The wiring went thru the car to the car's battery. Two reasons - one for security and the other just to not have to own and maintain 2 batteries.
Winches and batteries are prone to sprout wings and fly. Bicycle cables offer zero security.
Well, for a non-mechanic type guy of 70 years old, it's not that easy. Actually, I'm much more of the "computer" type than "mechanic" type...….especially at this age. Years ago I was somewhat different.
We have AAA and will call them to change a tire, battery problem or tow. That's what we pay a yearly cost for. We also pay an added on cost for any boat trailer problem while taking the boat to a lake.
Actually, I wasn't sure about changing the right brake/turn signal light, but did it. Wasn't easy, but I did it. The trailer shop, that we took the trailer to for electrical check/repair, did change the left one, but not the right one. Left one is an LED lights type, but the right one was a regular light type. So, we bought the right LED one online and it fit perfectly.
Drilling the holes for the plate the battery sits on isn't easy and really tired me out. That job isn't done yet. Still trying to make the decision whether I will TRY and take off the old manual winch and install the new one OR let a trailer mechanic do it and pay for that.
We already have a dual-battery set up with two Starting Batteries on our boat. I take them out of the boat at the end of the season and keep them charged up, during the winter months, with a very good Battery Maintainer. The security cables and locks we have, are pretty heavy duty, however we'd take the battery off of the trailer and take home, when boat is in it's storage spot in-between times going to local lake. I'd check the power of that battery at home and recharge if necessary. I don't have any problem doing that. And, we put a yellow sticky note on the dash of our Durango reminding us to take the battery with us to storage when hitting the lake. Anyway, having securing cables wrapped around an item and locked is better than having no security at all!
We bought this winch because my wife just doesn't have the hand/arm power to use a manual winch anymore. I simply don't want her to hurt herself using the manual winch.