You could carry some blocking to to put under the rear of the trailer frame to support it as you drive off.
That is usually not ideal, depending on the ground you are parked on, the blocks may or may not go under the frame.
The probably best option would be a trailer tongue jack installed on both sides of the trailer at the rear to support the rear of the trailer as you drive on and off the trailer if the ramps with the supports welded on will not work for you.
The ramps with the support legs can also be a pain if you are on uneven ground, sometimes I have had to push the ramps down with the bucket to get the ramps down or when you load the machine you can not pick the ramps up till you move the trailer forward a couple feet.
It is a real issue, I have seen the rear wheels of the truck picked completely off the ground and watched as the operator froze up and stopped the machine while the rear wheels were off the ground because the truck and trailer were running off. When it starts to move you have two choices that have a much better outcome than stopping, either get the machine on or off the trailer. And this is not just a pickup issue, I have seen the drive wheels on a tractor trailer lifted off the ground as well. It all depends on how long the overhang behind the axles is, how high off the ground the overhang is and how heavy the machine you are loading/unloading is.
Here in WVa, nothing is flat. Having the tow vehicle drive wheels off the ground on a slope usually has a bad outcome for something besides your under shorts.