What to look for when buying a camper

Check the operation of the 3 way fridge.

"What other things should I be wary of considering its age?"

Everything else,......... gearbox, brakes, steering, diff. Check for rust and/or rust repairs (body bog etc), water leaks into the sleeping area, unexplainable rattles and other unusual noises.
Drive it somewhere quiet and see what happens if you take your hands off the wheel, does it stay straight or wander off line, It may need a wheel alignment.

Make sure that everything works, both the driving stuff and the camping stuff too. Look at the condition of the poptop canvas, not cheap to replace, check the gas bottles and hoses for age and condition.

Any vehicle that is around 30 years old must be purchased with care simply because of its age.

Hope this helps.

Disco.

As well as a full mechanicl check which you would do on any vehicle..
Check out the condition of the'pop-top' material, and how the roof seals when it's down.
Check out the integrity of the furniture timber work- and the fastening and fixing of the furniture (this tends to loosen up on roughish roads)
If it has an upright/front opening fridge- think about ditching it and putting in a chest type fridge.
We recently ditched the Engel front opener- and put in an equivalent size 'chest' type fridge. I reckon it uses half the power- and it can be utilised far more efficiently than the upright!!
28 years old is a bit 'long in the tooth'. How many kms ?? Waht sort of work has it done ?? Has it been near salt water ??

Good buying !!

Toyota Hiace is an excellent choice for base vehicle, strong body and chassis, bulletproof engine (good for 3-500k).

Basically the same design from early 80's to early 00's.

Older Hiaces last way better than older Nissan and Ford/Mazda, and quieter than Itchymickies.

Usual mechanical checks, except that engine access is restricted, so oil and water leaks are difficult to see/fix from above.

Original tyres are a bit skinny, but you can fit 80's Falcon wheels cheaply.

The things I'd seriously check are the things that **** you off when travelling. Do all doors and windows open, shut, seal? Any RATTLES? Is the interior and roof in serviceable condition?

Front open fridges are fine, and gas ones are silent. Hey, if it's cheap, got a fridge, a bed, it's perfect!