Hi DawgWhat a shame. I had similar experience finding somewhere to camp in Isa. Turns out that you can (at least the year I was there) overnight stay at the visitor information centre complete with showers which come with hot water for an extra $2 per three or four minutes. HOWEVER, a few km north out of town, on the Barkly Hwy, parking was available at the RSL for the asking. Was handy walking distance for a cheap meal too. This was just before the rodeo hit town, so it was a given they were accommodating travellers. I was outa there before the cowboy circus, so all went well there for me.
We used to be able to camp at the Rodeo grounds, but that has disappeared since the Rodeo moved indoors, the Showground has even managed to get the showies off side, they were kicked out of the showground on the sunday night immediately after the show and had a three week wait before they could get into the Alice showground, to commence the Territory circuit, most of those rigs are too big for caravan parks anyway, and so were taking up the free camps out of town. I was told there was even talk among the Showman's Guild of boycotting the whole northern Circuit, from Blackall to Darwin. Apparently the showground commitees in the Isa and Alice are not allowing even the showies to camp at the showgrounds except during the actual show when they are charged a fee of thousands to be there.
I don't know if they have moved the information centre or not but when we were there a couple of months ago I could not have parked my rig any where near it. I have heard of the RSL but forgot about it.
Unfortunately The Isa has always been the fueling point for vehicles going West, Barkly Homestead having priced themselves out of the equation, unfortunately since Coles have taken over the Shell roadhouse at Tree ways, and priced fuel there (in their usual money grubbing way) to be comparative with other service stations in the area, that is the same rate as Barkly homestead and almost 40c a litre dearer than Tennant Ck 25km sth. and the roadhouse at the Isa appears to be following the same pricing schedule, all things taken into account, the adjacent towns of Cammoweal and Cloncurry seem to be the only choices to spend your money in, though the shopping choices in Cammoweal are severely restricted both for price and product.