Don't plan the route, just have vague idea of where you might want to end up and perhaps visit along the way.
And then be prepared to change it on a whim.
You only need the most basic of maps for that - I still have the two bob Esso map of Europe which was all I needed to get around half way round the world and back.
Even with SWMBO navigating!
You can't get lost if you have no fixed destination, although sometimes you might not know precisely where you are.
And a big trip is no big deal, the Ozzie speedway riders who rode in Edinburgh many years ago drove up each year in their old Ford Thames van, with only short sea trip between Darwin and Singapore? as deck cargo on a tramp steamer.
And they managed to do it without a camera, phone, credit card or GPS.
Just a long day on the way to the office!
Over the whole trip 150 miles a day allows you to enjoy the trip as well as stopping anytime it takes your fancy.
And IMHO you never want to be chasing a deadline when you ride on public roads, for whatever reason.
I prefer to travel as light as possible, tent/ shelter only for when there are no cheap digs available, and in Europe most camp sites seemed to have cooking and laundry facilities and usually somewhere undercover to sling a hammock, so some places no need to take the kitchen sink.
GB pounds and US dollars seem to be universal currencies and are usually more welcome than a credit card, so a good stock of readies hidden somewhere secure and safe might be a good idea, dependence on plastic alone might be a problem.
Usually a good idea to have at least two to three times as much funds as you think you will need available to you, things seem to get expensive if you need them in an emergency!