Right now the weight is still on the wheels and each additional load strains the suspension. Most trailers have pneumatic load balancing, so the bed drops with the load and then slowly pumps back up. Because of this a free-floating hydraulic ramp is needed. These interfaces are finicky and an unnecessary bottleneck. I've managed to get a 5 ton lift stuck on the ramp before.

I would put anchor points akin to trailer hitches on the back corners of the bed. The driver backs up to the bay, aligns the posts over the hitch, and hydraulics lift the hitches until they mate with the posts. Next they would lift up the truck bed, pull the truck back towards the bay, and set it down in a grove so the bed and warehouse floor are perfectly aligned. It would be similar to how a u-haul ramp mates with the truck bed (https://youtu.be/Ch7ukPPtZOI?t=46s), except you would be mating the truck bed with a building.

You could also have a giant drawbridge style ramp that lowers down and anchors to the back of the truck bed. It could double as the bay door. You could also add in outriggers that hold the bed at one height during loading. Alignment would be tough. Possibly the outriggers could sink into divots in the ground and shift the bed into position.

Both of these would also add a full width mating, which would allow for multiple bots to load at the same time.

Heck, I like the idea of having 4 hydraulic lifts, one for each corner of the bed, and have them lift the trailer up until it is flush with the warehouse. This would allow for the added perk of making taller, 2 story trailer beds and loading in two sets of shelves.

There are infinite possibilities, but I would be many of them are cheap enough to be worth the investment. One this is for sure, operating a lift is boring and I have way to much time to think on the job.