I have a 60L sprayer (I think that's about 15 gallons). I built a small steel frame to hold the sprayer, and put it directly on the 3ph. I wired a switch to the dash to turn it on and off, and a waterproof socket on the rear to easily attach it.
The sprayer was cheap - I think around $100USD. It came with a small boom as well as a wand. It's excellent. Main issue is that the wand isn't long enough to easily use without getting out of the seat.
The fab of the 3ph frame was really easy - it's basically two L shaped brackets, that sit under and tractor side. A section of pipe sized to go into the 3ph balls, welded across the two Ls (under them, so my dodgy welding isn't put under too much load). Then a ratchet strap from the end of one L, up over the tank, around the other end of the L, across the the other side, then down to the end of the second L. Tightens it all up and holds the tank in. Then I tied the tops of the two Ls together, and build a small box that the top link pokes through, and just put the pin in the other side of the box. It's all very light and easy to move around and put away. Previously I was putting the sprayer onto the 3ph forks and it was a massive pain to tie it down and set it all up. This way, it all just works easily every time. Worth considering for you.
Think hard about an FEL. Sounds like you have enough land that you'd use one. They become your mechanised wheelbarrow, they lift everything you used to lift by hand, they move mulch and dirt, and with a set of forks they unload everything from everywhere. I've never heard anyone say "I wish I didn't get an FEL on my tractor, I never use it." I've heard plenty of people say "I wish I'd got one sooner, this is awesome". But I think I see in your signature you already have an L3800, so you already have an FEL on that?
A carry all is good, a small trailer better. I have both (the carry all is just a pallet that I put low sides on, the small trailer doubles as a large wheel barrow. It looks a bit stupid on my B2601, but it was right-sized for me BX. And it only cost $100. Of course, a FEL is also a carry all for tools etc. And firewood. Nothing better than loading your FEL at ground level, taking the firewood where you want it, and lifting to waist height to unload.....no more lifting for me. If you don't stack tidily, then even better, you can just dump the FEL into the wood pile.
A BX is OK for general transportation, but they only transport one person safely (and even unsafely, it's uncomfortable with two). And they're slow. How big is your property? The B2601 is waaaaay faster. I only go 1/2 km down the road to mow the community land, but I really notice the difference in speed.
If you're only backup mowing, and you really don't want/need an FEL, actually a side by side would do a lot of the stuff you describe better. They're closer to the ground and more comfortable for spraying, faster and better for transportation of 2-3 people, better for carrying tools and junk around. And they usually have a cab of some sort to get out of the sun and rain. They don't need a carryall because they have a tray.
Other uses to justify a tractor (but you already have a tractor - an L3800?):
- FEL of course
- PTO mounted chipper
- snow moving
- boats, trailers, other things that need to be pulled
