My itinitial plan was the following:
Visit Sabah (Mt Kinabalu, Sepilok, Danum valley, Pulau Sipadan)
Cross by sea (with a prearrenged visa) to east Kalimantan
Visit Kailimantan (Derawan archipelago, Wehea forest, cross borneo trek?, Loksado) and go all the way to Pontaniak
Cross overland to Kuching and visit Sarawak
Cross back (visa on arrival) and connect to Sulawesi from Pontaniak
This may not seems very efficient but basically the trick for me is to first use my 30-day prearranged visa for Indonesia, then exit to Malaysia and neter again to obtain a new 30-day visa on arrival, to be extended later for another 30 days, thereby allowing me a total stay of 90 days, which is definitely not too much for vast indonesia.
But things seem to complicate when it gest to transport:
How to connect to the rest of Kalimantan from Pontaniak?
How to connect from Ponatniak to Sulawesi?
Alternatively, I could just do Sabah > Sarawak > Kalimantan from west to east and proceed to Sulawesi. This means I'll only get a visa on arrival in Enkitong, and extend it once. But then I might go to peninsular Malaysia from Java and then back to Sumatra, getting a new 30-day visa on arrival, and summing up to 90 days again. But then I still have the problem:
How to connect from Pontaniak to the rest of Kalimantan?
Are Sabah & Sarawak well connected by road?
Thank you very much in advance for you much needed advice! :-)