I haven't read the other thread (sorry, can't find it) so I may be repeating what others have said. Also not really sure what type of advice you are looking for. But will have a go at answering.
Firstly, I think it is probably much easier to do a road trip with a 6 month old than say, a 2 year old. Once they get to about 18 months long car journeys can be difficult - up to about 3ish when it becomes easier to amuse them again (at least it was with my DS). If you don't go now it may be a long time before you think it is possible.
Try and arrange the driving around the baby's usual sleep pattern - they often will fall asleep in the car outside of their normal nap time and that really does give problems later (screaming baby in a hotel room late at night who is overtired but due to having naps at odd times off the day can't/won't go to sleep!). Drive when they usually sleep and if they are asleep keep driving.
It is better if the non-driving parent sits in the back of the car with the baby, to keep them happy when they are awake. Very simple toys etc to keep them amused in the car, nothing noisy as it will send the driver up the wall - also a bit dangerous sometimes as it really can affect your concentration when driving. My son had some books with the flaps that you lift up that amused him for hours, he also liked the one touchy books with different textures. Other simple things like stacking cups etc were good for the car. Anything really that your baby usually enjoys will be good, as long as it is not messy or noisy.
Wrap up a few little things to open every so often. If they get really bored bringing out something new, especially if it is wrapped up a surprise will pass on a bit of time (even now when my DS is six he has a couple of surprises for long journeys - although he is obviously wise to it now and asks for them as soon as he has his seat belt on 
).
Although it is a road trip don't be too ambitious with the driving - you will probably have to make more stops, which takes time, and it can be incredibly boring if you are the one sitting in the back. Much as I love my DS I can't say I really enjoyed really long trips at that age, keeping a young child amused in such a confined area for a long time.
This is all about being in the car I realise. Other things - book all hotels in advance, no fun traipsing around with a child in an unfamiliar town trying to find somewhere suitable. If staying in hotels we always book somewhere with a balcony/terrace attached to the room, once the baby is asleep you have somewhere to sit together and enjoy a bit of time to yourselves without disturbing him/her. However, don't make too many 'optimistic' assumptions about what the baby will or won't be doing then as I did (e.g., s/he will be sleeping through the night, we can have a meal while he sleeps peacefully beside us - yeah that happened 
).
Hope this is some help, sorry if I'm stating the obvious or repeating the other thread.