Your best bet is to find the most rigid base/rails possible, the more rigid and sturdy the easier the setup. What I have is technically a 8' "cable ladder" I think. You can stand in the middle of it on a full span and it doesn't move even 1/16"
Agreed, an absolutely rigid ladder is ideal. Everyone tends to make do with what they have handy or can be found easily, so we mostly use things that basically work but could be better. I've tried most of them, wood ladders, aluminum ladders, unistrut, rails on end brackets. BobL gave me the idea for a heavy duty unistrut "ladder" with threaded rod for rungs, but ended up being a fail because the Home Depot unistrut was slightly bent. Good idea otherwise and can bolt on extension pieces for really long logs. But still want to get some steel tubing and weld up a rigid ladder one of these days.
This! High carbon steel seems ideal. Gonna be heavy though!
I don't mind. Everything's heavy in milling. Once you start moving big 250 lb white oak slabs around, everything else doesn't seem so heavy anymore lol. I'm not hiking through the woods to mill or anything, so a heavy guide ladder is okay. I worked in an orchard for a bit picking pears and apples 35 years ago and we used heavy straight steel ladders. Those would have been perfect.
Go fine one.
A pair of 10 or 12' lengths of decent gauge 1x3 or 2x3 steel tubing and a bunch of pieces of steel angle spot welded as rungs and it'll be easy enough to make a good one. Just opportunistically waiting to find the steel cheap, ideally in the .30/lb scrap at our massive local steel recycling yard. They have so much industrial steel there, most of it too heavy for my purposes, but sometimes pallet racking and other useful tubing.
Cheap is using bed frames. Box the angles. It's all good stuff if you find the old ones. Commercial racks are the bestest. I get mine for free on roadside trash piles. Makes good anything like shelves, racks or anything rigid that needs to flex very little. Spend your steel money on electric and welding rods. Car rims lag bolted to V blocks make good log stands. I’ve used extention ladders folded up. An old aluminum pick plank also works pretty good with wood rails screwed to it. I'm sticking with my I beam ladders in fifteen foot sections. They are stackable if need on banana logs. Also used them side by side on fat logs for the wider center cuts. Good to get that straight flat run going again.
