I have managed the Robinson entry a number of ways. A few times I've convinced Canadian authorities to jus let me enter the park (out of season) via Mudro. They were reluctant but I explained how close the entry was to my house and they relented. I have paddled up to PP and dumped my deposit in the box and left with a permit the day before. I have added cash to the self-permitting station after my trip.

To get a RABC on the spot you need to go to a Canadian Customs station. To my knowledge the only station near the park is at Crane or LaCroix on the west end. Quetico Park personnel have no customs duties or authority..

For the B-dub I just fill out two self-issue permits- a day permit for the day I enter the park and a entry point #30 (entry from Canada) for the day I leave.

Offhand I think the journey from Robinson to Mudro is greater the 14 miles.

I have visited the site referenced by Mossback on the north end of Robinson. It is at a pinch- a level  sandy point with nice trees that makes a narrows with a couple of islands closing the pinch. Nice location though a touch beaten down. Great fishing in the area. The aforementioned island site has more space, but there is plenty of flat tent spots on 'Sigs" site.