HI,
If you go the route of a road base, even one built specifically for the Aero, you'll soon run into the very weight versus suspension spring rate issue / question you mention.
When I looked around for my own road base, having hired or borrowed before, I was soon advised that even the lightest spring rate rubber in compression axle that is used on the majority of trailers is substantially greater than the weight of the Aero; even with: a full set of spars, spar bag, a full set (all three) sails in bags, foils in padded bags, bottom & top cover all in or on the boat. I found I could jump up and down on my trailer axle and it barely deflects, and I'm 70 Kg!!
In the UK we have some of the most pot holed roads in the western world.
The conclusion on jarring the boat I came to was to:-
Fit the largest diameter wheels, 10" in my case, available for the road base.
Put foam on the 1st trolley X-Bar, the one that goes under the mast step drain hole. The boat tends to oscillate about the gunnel arms unless tied down securely at the bow.
Remove the trolley wheels when trailing. Even with 10" wheels they are only 2" off the road. Go down a kerb or over some speed bumps and suddenly the whole rig weight transfers through the trolley wheels and gunnel arms.
And drive carefully.
Hope this helps.