You could boost the temp and add a mixer valve, that's how I deal with the VERY slow recovery time on my heat pump hot water heater.
Set temp of the tank is 170, the mixer valve is set to supply 120 to the house by mixing in unheated water. Here is a pic.
I think the op has the idea to use the first tank has a tempering tank. It brings the ground water up to room temp. Strip the insulation off and plumb it in. My dad did it when I was a kid. Moved the heater to the basement and put the tempering tank next to the wood stove
In our new shack we have a 40 gal heater, we will need more gallons than that soon when my new whirlpool tub is finished (waiting on surround walls). I am not sure which way to go now. Temper or simutaneous or recirculate?
A tempering tank won't create more hot water. It will save on your energy bill. My dad used a pump to service a bathroom in a really long house he had. It worked good. Something else to think about on two heaters. I put a second tank in my last house to service the new addition. Now it is rental property. I have an additional worry and expense to deal with. A life lesson I'm learning is I have bought some things or added some things that I may not be be able to afford to maintain or fix when I get old.
I've been thinking about putting in a small (110 volt, 6 gallon) electric water heater under the kitchen sink to service it and the dishwasher. I'd have it plumbed in series with the LP water heater in the basement. The problem I think I'd be solving is how long it takes to get hot water up to the sink since it's so far away. By my thinking, if I feed hot (or soon to be hot) water to the electric heater we'd have nearly instant hot water and not use much electricity since it would be pre-heated. I like the idea of dual heaters in the basement but I feel like (I haven't ran the numbers is what I mean by feel) it makes more sense to have them as close to the point of use as possible.
