That's the spirit. At the same time, sometimes things do not work that way anymore, and there is no point in denying that age does things to you. From my own reassuring experience I can say that I have quite a few cycle touring friends who do pretty ambitious trips, and happily camp in small tents.
There are a couple of things to consider, however. As far as the cycling goes, climbing is the part that gets the hardest with age, for simple physiological reasons. You can delay the decline by training, but not stop it. So get sufficiently low gearing (a big hurray for modern mtb gearing), and most of all, travel ultralight. Climbing is all about beating gravity, so the less weight the better. This is where the real comfort will be, not in take more stuff 'because you like your little comforts'. That said, a slightly roomier tent makes life a lot easier if you are not as flexible as you once were. So a Terra Nova Laser Competition may be very light, but also too small. An MSR Hubba Hubba HP tent at 1.9 kg is just a bit heavier than your typical solo tent, but not by much. And it is a lot more spacious. A Helsport Ringstind Light 1 is only 1.5 kg (and the much larger Ringstind 2 is still just 1.7 kg), and also rather taller than many solo tents. Thin mattresses used to be a problem for aging backs, but the new generation of insulated air mattresses (Thermarest Neoair, Exped Synmat Basic, Exped Downmat - in order of increasing warmth) are both far thicker and more comfortable than the old thin self inflatables, but also lighter and more compact to pack. The new Exped air pillow at 85 grams is superbly comfortable.
Willem