Yup, a set of ALKO 'Outback' rebound springs (no need for shocks then), a 45mm square axle and a wheel / tyre combination to suit the desired ride height.
If being used as an off-roader, then you may want to consider a stone guard up front and depending on whether the current trailer is galvanised, a layer of sound deadener tar underneath as stone chip protection.
Also, depending on the level of off-roading, you may want to change over the coupling from the 50mm ball coupling to one of the 4wd hitches, ie tregg, Hyland, Orac etc...... so the beast doesn't seperate from the tow vechicle prematurely
Maybe look at the dust integrity, may need the odd seal installed around the tailgate / bed base to keep the dust out
Hope it helps.....