1.5 acres. is not a lot. and you might be better off with just a regular finishing mower. even a cheap riding lawn mower or garden tractor. vs a zero turn. so you could add a tiller. or buy ATV or garden tractor size, pull behind equipment.
if you really need to do a lot of digging, just "rent" a min excavator or small TLB or like. and just save up projects over a year or couple years, and just rent and do everything in a couple days, and take a couple days off of work if need be to do the work.
they do make FEL (front end loaders) for garden size tractors.
but to be honest, once you get flower beds and landscaping done, your done, for any were from 5 years to 20 years before things rot and need to be redone. and in between that time, you will be using small little tillers that look something like a weed whacker. due to no real space to get a tractor in to the areas without trying up stuff. and you will be using small little hand shovels to plant stuff, and metal garden rakes to smooth things out.
get a zero turn and just get a hitch welded up on it. it is a working machine, make it so you can use it, and stop fussing over looks. or get a riding lawn mower, in garden size ridling lawn mower. so you can put some attachments on it, like a tiller. or pull a small cart behind it. or just drive truck through the yard.