there be a few threads i have came across in last couple months for "off set" mowers to help make a wider mowing path.
myself have also looked into this. for me it came down to either paying for a 3pt bat wing finishing mower. ((2 or 3 decks, with 3 blades per deck)) or going with a "gang reel mower"
a gang reel mower, seemed like best option for me, and would give a better cut and followed the hilly terrian i have much better. vs a finishing mower wider decks that would end up scalping and cutting into dirt more often.
also once i got into the larger bat wing style finishing mowers. the HP required for tractor went up rather fast, vs "gang reel mowers" that require a lot less HP to pull and use them.
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other words to above....
wider finishing mower deck always quickly sounds nice. until ya get into hill terrian. then once you realize how much scalping you are doing. and how much extra care you have to take. wider finishing mower decks quickly go by by. and then multi smaller decks come into play.
if you had pure flat land say like a golf course a single wider mowing deck might be awesome on another hand.
with multi smaller decks, come added cost of hyd lift for bat wing style mower decks. and then the old neck / back pain of twisting around constantly to see how things are as you mow. due to needing to be on rear of tractor.
off set mower can be nice. i tend to see ""ATV"" finishing mower decks with pretty simple way to off set them. and a gas engine on them. but normally in this situation it is just a single mowing deck being pulled.
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some additional things to think about. i tend to see more threads here on TBN about folks cutting seat time down by a good amount with a commercial grade Zero turn mower ((not a cheap small city yard zero turn mower, but a beefer zero turn mower)) due to ability to make quicker / easier turns. and applying power were it needs it. and being able to see were you are mowing. they are all small little things. but when you make 100's of turns and mow around multi things it all adds up.
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on other hand if you are a tinker and like pulling stuff apart and putting it back together and building things, and ya have the tools and know how. i would say go for it. could be a very fun project. and work great for you.
i just know for me. while i like to do above, not enough time for this type of project. and if i had the cash i would sink it into "gang reel mowers" if not a bat wing rear finishing mower. if not a larger commercial grade like zero turn mower.
if it was a zero turn mower, then, for me it would be automatic to have a tractor as well. having 2 machines can be handy, and can mean getting R4's or R1 tires on tractor, while leaving turf tires on the zero turn. so you do not tear up the grass as much.
i hate to say it, but with finishing mowers, if the grass is a little bit to wet or a little bit to tall. it can quickly cause me to change to lower gears and set a higher throttle speed. to keep cutting the same width. and things can get to a point were i need to start taking "half cuts" vs full deck widths of mowing. if you don't have that much problem with what you have now with what you have to mow. an additional off-set mower might be just right for ya.