looking at google maps for Keena, CA, looks like your right smack dead in middle of mountains / hills.
you are already have the 35HP 4x4 tractor and need something smaller for tight smaller areas.
for myself, i went out and buchered the tree's lower branches, and do so once a year. so i can run an old allis chalmers CA tractor under the trees to mow. also removed some other stuff that no longer care to deal with. flower beds and like.
for the wife though, and dealing with 25% slope hills. and she not wanting anything special. and just a simple cheap riding lawn mower.
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if you didn't have the 35hp tractor a zero turn, more of a commercial unit might be better suited for 5 acres. zero turns cut / move faster. and in that reduce mowing times. and with zero turns with mower deck out in front easier to maneuver around stuff and corners to mow closer to obstacles when mowing, so less weed eating to be done (big plus)
with not wanting a 4x4. a zero turn might be a better deal for traction. riding lawn mowers rear wheel drive and motor weight out on front tires, you simply rely on person weight, and possible fluid filled rear tires, or wheel weights or a weight box on back or tire chains. to keep traction. on other hand for a zero turn, motor weight is on the rear driving tires already. and you should be able to add chains or weight to zero turn rear end if needed for traction.
riding mower 2WD (rear end drive) hills on this farm were kinda of a joke, in some cases only way to mow hills was running around the outside then make a quick sudden drop down some of the hills trying to mow. just no traction to get up the hills and/or simply not enough power to get up the hills even if you added weight / tire chains.
i simply do not have much hope in 2WD riding lawn mowers, built cheap for cheap and for small city / town lots. grab something cheap, toss some cash into filling rear tires with fluid or wheel weights, and grab some chains. and go at it.
about the only thing left would be a self propelled mower, were you can buy (meh forget technical name) a little wheel/s and foot spots. and acts like a mini trailer, were you stand on it, and grab on hold to the handle bars and go at it standing up. (zero turn with out a seat), (riding lawn mower without a seat), (deck, engine, drive wheels a couple caster wheels, then mini trailer you stand on).
and one other type... i just remembered. i forget the company names. 2 wheel tractor (self propelled). were you can swap out the fronts for different attachments. from finishing mower, to edger, to tiller, to other. and you walk behind them. take a larger riding mower engine drop it between 2 wheels, add a shaft and connection out in front of it. toss on larger 48" finishing mower deck vs 2 foot regular push mower deck. grab the handles bars and let it pull you around as you walk behind it.
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i would push for zero turn mower. if i did not find the allis chalmers 1954 tractor, AG tires on back, and narrow front end (tricycle in essence) it would have been a zero turn here. riding mowers beat you to death, and as many times you need to turn around on corners and at ends of mowing path zero turn would shave a lot of time off mowing. it gets old making large figure 8's to wider turns on a regular riding lawn mower to cut grass. to many times how much stinking longer will this be as i took a turn on a riding lawn mower. 6 to 8 hours pending on how tall grass was down to 4 hours. is a large difference.
post some photo's, get the wife on here. and read through the comments. look at some youtube videos of zero turn and hills.
talk to a dealer see if you can get a trail, if not happy return zero turn.
mowers will be going on sale here soon enough as grass just starting to get green and starting to grow.