Will. Not sure what you mean with " thick tires " .
The rust at rear of the trailer will not matter for the drive home, make sure the tyres are properly inflated and are NOT perished.
What I mean by that is have a look around the tyres and make sure they are not all cracked up and still feel like rubber.
If the tyres are starting to feel/look like leather, than the trip may be a bit much for them, try and take a spare, if you don't have a spare
I would more than likely have one here that would match whatever the type fitted, brooker should be HG Holden pattern, with 5 studs
IF it's the rims without studs, I still should have a spare to help you out, PM me for address.
Try and keep your speed to around 80 k's max, and stop about every 10/15 minutes and feel the hubs to see IF they are getting hot,
IF they are too hot to hold your hand on them for 10 seconds, you have problems, if they are cool it's likely you could go faster.
Good luck and take some photos of the boat and show us.
Frank