I get supplies from Lincare but I think they overdo it, because I haven't been able to use all the things they send. I wash my hose and headset in vinegar every couple of weeks. I've never replaced them. I have an extra hose here in case I ever need it. The nasal pillow I wash daily with mild soap. I used to replace them every couple of weeks, but then realized there was no real reason to do that except to use up more Lincare supplies.
I feel like I have plenty of supplies for the next few years and the last few times Lincare called, I didn't order anything. No reason to. I have dozens of filters they've sent me and I don't really need them very often because my apartment's air is clean. (That will probably change when I'm living in the van.)
Anyhow, to answer your question, if I need supplies while traveling I'll call Lincare and have them sent to General Delivery of whatever post office I'm near. That should do it.
The alternative is to have them sent to my mail forwarding service, then have them sent from there to me wherever I am. I don't see any reason to do it that way.
Another alternative is to buy the supplies from Amazon... but then I'd have to pay for them instead of having my insurance pay for them.