needs a "foot"...
I know that the crane I had on my K20 would lift 1000lbs fairly easy,but yes,it is a bit scary when you have that much weight on one corner of the truck only,and then it shifts to the other side when you swing the load into the bed..I once lifted a dodge ramcharger's rear off the ground completely so we could cut the rear axle out,and my K20's drivers side front tire was 6" off the ground!..(my crane is on the passenger side rear of the bed..)...
I did make a "foot" out of square tubing that slid inside each other with a bumper jack base on it,bolted right under the crane,to the frame of the truck,that I could adjust and pin into position, to keep the weight off the springs and frame..its similar to a trailer jack--one of those or a bumper jack would work as well...but I often lifted things in without using the "foot",and learned though its very possible,its not the best thing for your frame rails....when I junked the K20,its passenger side frame rail was 2" lower than the drivers side!

--I guess it didnt like the weight I put on it..--funny thing was the truck still drove fine,and would go straight ahead when the steering wheel was "straight ahead"..but my frame was paper thin in places due to rust,so that was probably a major factor...still a good idea to use the "foot" though,to prevent bending anything..
If you do make a trailer out of it like I did,I'd be sure to ALWAYS use the "foot",and only lift things while the trailer is attached to the trailer ball on the "tow" vehicle..you might need to bring a few jack stands to place under the corners of the trailer frame(or make something similar) to stabilize it and keep all the weight off the springs,and keep it from wanting to pop off the trailer ball....
.My trailer has COIL springs!!--not my first choice,but I already had it--I'll just have to be more careful to set up the "foot" and jack stands at each corner(if needed) to make it as safe as it was on a 4 wheeled truck.(if nessasary I may modify it to leaf springs,or maybe just "dead axle" it--it might be too "bouncy"--wont know until I get new shocks and do a test tow!)...
...I'd prefer to have it on a driveable truck like I used too in a way--but like you noted,a trailer needs no insurance,and its a lot cheaper to register than a truck,and you can tow it with most ANY vehicle thats capable...since I did not use my K20 every day,it was an uneeded burden to have it registered and insured all the time,just to use it a few times a month..Either way,the crane and flatbed are a handy thing to have around--it saved me a lot of hernia's,and paid for itself many times over--I bet I scrapped 1000 bucks worth of stuff I got for free with it,when people called and wanted heavy stuff removed,after learning I had the crane,and would do it for cheap or free..

...one of the FEW things I made that actually worked good,and turned a profit!!
