You shouldn't have any problems at all John, just remember the 7P's!
It's sometimes nice to have a ride buddy, but you'll probably read a lot of trip reports on this forum from guys who ride solo..... it's down to the individual.
There are some considerations of course: what bike are you taking? I read on other threads you were thinking of getting a 125cc yes? If you do it on a Honda Wave then breakdowns will not be a problem as most Thai's were born on them and can fix/bodge a repair with their eyes closed, but if you pick an older or unusual machine you'd better be a bit of a handy spanner-man yourself, just in case.
GPS V maps: I can only presume you will get all the info you need from Cap'n Slash's site: I cannot load his site here because of dreadful internet but I do know his stuff, so either print off his maps or buy yourself a GPS and download! Me, I still use paper maps and a scribbled bit of paper and find myself getting lost and backtracking a few times....... but that's half the fun of it, communicating with locals to get directions etc....... if you've never had a head-scratch at Thai folk trying to give directions, your life is lacking!!
Your particular tour: if you do the back roads, once you find Dan Chang and decide to head for the 105 using back roads you will always be safe in the knowledge the main Bkk - Chiang Mai highway 1 is only a few miles to the east of you, so if you screw up you can fall back on that to take you all the way to Tak, and then start the adventure again! (You could take the 1 all the way from Chai Nat or Nakhon Sawan if you really wanted, but you'd be missing out on a lot)
Plenty of hotels and guesthouses along the way..... when you have planned your route let us know as I'm sure there will be overnight recommendations from some of the good folk here.
Return route? Chiang Mai - Lampang - Den Chai - Nakhon Thai - Lom Sak and then over to Khon Kaen, Khorat, few days in Pattaya then home via a few days in Bkk...... all good fun too! :wink:
Cheers, have fun! Oh, the 7P's? Prior Proper Planning Prevents Piss Poor Performance!