May sound silly but wear good cycling shorts..and do not wear any pants underneath the shorts...
As for your bikes..on the Speed D7 change the chainwheel at the front to a 42 or 44 ..You will find you can get up most hills and travel more easily with lower gears..I do not think you can change the rear cassette to one bigger than 30 because of the Neos derailleur..If the other bike has a Neos derailleur also then again change the front chainwheel to about 42 or 44...If the Mu P8 has a normal derailleur you could change the cassette to an 11 to 34 but you might need a longer cage derailleur..
If you are going to carry a heavier load then it might be worth getting the Dahon front pannier rack..and get the Dahon touring pannier rack or any larger pannier rack will fit with a bit of work..I would get the rear wheels on both bikes rebuilt by a good wheelbuilder but no such need with the front wheels..
I think both your bikes will be fine for touring...as long as you just make a few simple tweaks..no need to change them..You can tour on any bike..I have toured around Thailand on my Brompton and now use an old Dahon 6 speed steel folder to tour there...tough as anything .Last month I met a chap in Bangkok touring on an old Raleigh one speed ..did the job fine..Hans Stucke has toured the world for the last few years on a Brompton..
I think both your bikes are fine for touring