Plenty self builds have this issue, my bus has 3 steps up into it but not a big issue. Left the bus handrails in place too so really easy to get in/out...I have always thought of Mitsubishi vehicles as being superbly engineered, however with regards to your post I honestly do believe that this particular cab/chassis has a chassis that is far too high off the ground to transform into a MoHo, you would need multiple steps to gain access.
Phil
Though I've not seen a uk version they do make a panel van and coach, so there must be engine access alternatives?Weather it was second hand or brand new the engine location would still put me off