I replaced the 35 year old Universal Atomic with a new Atomic in 2011. I prefer gas engines as the smell of diesel makes me sick.
Access from inside is now very good, in the original it was difficult to even see the morot. Remove the panels for access to most stuff. The steps can remain in place.

From the cockpit the engine can be lifted out easily. Access to everything is good.

I converted two foot wells into battery space. Two Trojan 6V golf cart batteries fir exactly into the space, each side. Easy to maintain and add water, check connections and so on. Golf cart batteries are available everywhere in the world that people golf. Each costs about $100, and last about three years if constantly trickle charged by solar.