I have problem's with my foot, really both feet at times....
I found that anti-inflammatory helps me over a the long term, I use a one prescribe by my doctor daily, as well as stretching the foot, and leg exercise's.... several times a day...
As well some type of ibuprofen & Tylenol, and alternate between them, so that you don't get any break through pain...
When we travel, I bring along those medical ice packs, you know the ones you sorta break and shake and it get's cold, I took them to Paris with us, and they were a blessing at the end of a very long days I took 8 with us, we both used them... you can use a over sized ziploc to put ice in and prop his foot on it at night... I suggest you double the bags if you are going to go this route, you don't want the bag opening or ripping and then the bed is soaked... I also bring therma-care wraps with us....
Find him a good pair of shoes to wear light weight, the kind with the built in gel cushions or memory foam... and there are these shoe inserts, that when you walk the you can fell the gel moving around under your foot, its kinda strange feeling, but really helps... I can't think of the name of them... I have a pair and they are completely worn out... If I can find the name of them, I will come back and add it here...
Getting in the pool will help, the weightlessness helped me when I was going through therapy...
I would plan a different plan of attack for your trip.... more breaks, pool time and such to give his foot a break as much as possible