Need suggestions for too small water heater in attic
I bought my current house in 2005 and paid a contractor to do an addition with new master bath in 2006. He put the electric water heater in the attic above the bathroom. There's an access panel in the bedroom wall about 9 feet up. The panel is about 2 1/2 x 3 feet, although I haven't measured it. I asked for a 50 gallon water heater because the master bath has a shower and large garden tub. Problem is, you can't fill the tub without running out of water. When I went into the attic I found a 40 gallon water heater. Lot's of finger pointing and no resolution at the time, just compensation for the cheaper water heater's cost.
Today, I'm trying to figure out the best way to be able to fill the tub with hot water. My life has changed and my knees would appreciate soaking in the hot water. The water heater is now 6 years old. Should I replace it with something larger? Or, put another tank in series or parallel to supplement it? There doesn't appear to be much additional height for the usual height water heater, but there is enough floor space for two.
In any case, I will need to get the new water heater up there. If needed, I'll screw some heavy duty hooks into the ceiling to hoist it up. I can touch up the hole afterwards with a little spackle and paint. Do professionals use a sling or any special gear to hoist a water heater? Would a Marathon water heater with plastic tank be a better bet because it is lighter or less likely to get damaged?
I have lot's of questions. I'd appreciate some "wisdom of experience."