An 05 model should already have the aluminium frame work under the lounges etc, if not and it is still finger jointed pine, check it out for cracked frame work from kids jumping off beds or jumping on lounges.
Just checked the usual, cupboard doors closing, drawers sldiing etc, gas works ok, under body stone damage. water tank, canvas etc. There are no real major faults to look for, just the usual wear and tear things, and an signs of abuse.