to add to the already good points about weight, this makes such a difference on things. I dont know if you have biked with the amount of weight you are proposing, but as you say, you are most likely older than others here. I am in my mid 40s, and the last time I did a long loaded tour was pre-kids, 15 yrs ago (down the west coast of Oregon, Cali)

From my experience of previous long trips, I improved my packing, and reduced reduced reduced, because any time you hit an incline, its a bugger of a job getting the weight uphill. I very much susupect that if I did the same trips now, my knees and legs would suffer much more than when I was in my 20s or around 30 (and I remember very stiff mornings and or ends of days)
All this to say, i very much second putting money into lighter tent, campstove etc etc. My tent I toured with weighed 7 lbs + (a 2 person tent that I had and wasnt going to buy a smaller one) Every lb saved makes sucha diff, so this that and everything that is lighter all adds up.

I very much suggest riding with the anticipated weight of stuff you would like to take, just to get an idea of if it doeable and or to see if it is just too much. Find some hills to try it on too.
Yes, get suggestions for a "dream high quality tour bike", but do think about getting new camping gear.

I cant imagine pulling around 75lbs, I honestly dont know or remmeber how heavy my touring kit was, but I suspect it was around 35-40lbs.

if you do not use these for night riding, I strongly suggest the blinky LED red lights tht attach to your seatpost, I use a white one for forward, they are very very visible to cars.

cheers