From Cairns, the inland route via Mt Carbine, is a good sealed road all the way to Cooktown.
After Cooktown, you need a vehicle that will stand up to lots and lots of corrugations. Long kms of big corrugations. That said, delivery trucks etc go regularly to Weipa, and some of the "locals" drive ordinary cars.
The "main" road - mostly unsealed - goes via Laura, Musgrave, to Bramwell Junction. There are some water crossings that should be fairly low, once the road is open after the Wet, and some are now culverted. From Bramwell, the Bypass roads are the "normal" roads. The alternative OTL Track north definitely requires a sturdy 4WD vehicle, good skills driving same, and good recovery gear. People do tow camper trailers on it, but the welding services at Weipa and Bamaga also do a roaring trade in the season!
There is a ferry service over the Jardine River. The fee for this is also a permit fee for access to the lands north of the Jardine.
The best time would be after the graders have been through!! Seriously, it is hard to say, because of the unpredicatable nature of the Wet season. If it has not been a huge wet, I would say May into mid June. From mid-June to about mid July is school holidays and there is the hassle of meeting up with other drivers who are in a hurry and do not drive to the conditions. Plus camp areas busy. After that rush dies down, the weather is pleasant and it is not too dry and dusty into early August, but the roads are likely to be more corrugated. From about Sept, up north, it starts to get hot, dry and dusty.

The road is bitumen to Laura.
Plenty of conventional vehicles and caravans make the trip.
If you hang around down south a bit until the roads are "Open to all vehicles" it will indicate that the road is dry and the graders have virtually finished their job. Go then.
Early is also the best time. The waterfalls are their best and the country looks great after the wet.
Later is hotter, dryer, dustier and rougher.
Even if the roads are "bad" they will still be passable with your motorhome. You may just need to slow down a lot more to look after the vehicle and tyres.

Cape York is a great destination and you don't need to be a "gung ho" 4WDer to have a great time there.

I would also strongly recommend this event. www.lauradancefestival.com/

Cheers,
Peter

Cape York main road.

There are a number of places in remote parts where I would take the Coaster we have now, but Cape York would not be one of them.

-- Edited by wendyv on Sunday 21st of December 2014 03:05:20 PM

Check my blog for our 20132 trip.
bkmcl.wordpress.com/2013/05/

Several very good tour companies do tours up Cape York, usually in a drive/fly combination. Outback Spirit is one company with a great product. (I have no connection but have seen them in action)

Repairs and retrieval are very expensive - and inconvenient - on the Cape. As I mentioned, welding services are in great demand. I suspect tyre services too!

Some travellers drive one way and pre-book to go back on the "barge" that services the communities from Cairns. This takes vehicles too. Others have to go back by barge even though they did not plan to!

I know a couple who went both ways from Cairns on the barge. It gave them a chance to visit Thursday Island, briefly, and they loved the boat trip.

With a tour group you are limited to the main attractions only.