I've got an 8k Warn on my gooseneck trailer, hook a battery to it and it'll suck a deuce or other fairly big vehicle right up on it. Easily the best trailer mod I've ever done, had the 30 year old 'upright' style winch lying around so I was only out the fab time...
That being said, I've loaded plenty 'cave-man style' with two come-alongs and some chain. Put the chain on the vehicle, pull with one come-along and then with the other when that that one is out of cable. The trick is to be safe about this, CHOCK THE WHEELS as you go because if you fumble around and the ratchets on these crappy 'hecho en chine' come-alongs they sell now slip you could do some damage with a big truck rolling back off the trailer, usually into/over the most expensive thing in the area if you have my luck!!
Hint: bring a tough friend that enjoys a workout, some gloves and a cooler full of hydrating beverages...