Yes, you can get full-spectrum lamps, I think fluorescent tubes are the most common but there are also brighter types (halogen, maybe?). I've done very little indoor gardening, but if you ask around among people who start seeds indoors, you might be able to get some suggestions. I doubt you'd need to add any heat, because your basement should never freeze. Citrus requires a winter chill (it doesn't grow in the true tropics), so a cool basement should suit it as long as the light is sufficient, but I think Carol has a point about it not producing well under such conditions. I don't know anything about avocados, but it sounds like her advice is good there too.
If you build your ramp long and with a shallow slope, you should be able to roll a plant on casters without the hand truck, which will mean the container can be heavier without risk of injury or toppling.
Alternatively, you can container grow trees that are suited to your zone such as apple, pear, or cherry without having to move them, or a zone 6 plant like peach, fig, plum, or apricot might be OK if you have a warm microclimate on your property or can offer winter protection. Almost all have dwarf cultivars that can be grown in a large pot. If you're not tied to the idea of a tree, hardy kiwi should thrive for you; it's a climber, so you'd need to offer some kind of trellis above your container, but it's quite prolific. Or try a pawpaw (not papaya, which is sometimes called that), a native fruit tree, if you like its flavor.
Just brainstorming here, sorry if my ideas are all over the place. I never had the space for trees, but I would really love to have a mixed fruit orchard one day.
(Edited post when I saw Carol's reply.)
