Ok, when you said travelling I thought you meant abroad. That makes your situation easy to deal with. Just return to Immigration on the day they request, get your stamp and be on your travels.
Cancel your existing extention before you leave then get a new Non Imm O on your travels. You'd be stamped in untill October on your return and then apply for the 1 year extention of stay.
That certainly isn't the norm at Vientiane, if they take your money and accept your application then you're good to go. They tell you there and then if you'll be denied.
It's 17 months with the 60 days extention of stay and there's NO financial requirements at the RTC Savannakhet for the multi-entry Non Imm O visa. Only the 60 days extention is from any visa or visa exempt