I have a similar sized and rated tractor to your CK35 and I have the Construction attachments forks rated at 1800 lbs.. That is all you need. You need lightweight forks. Not heavyweight forks. These forks weigh 285 lbs.. There are several lightweight brands available. You can pickup a little over 1100 lbs, why would you need forks rated to 3500 lbs? You are just going to lose payload capacity by having heavy duty forks, because they weight more themselves.. What matters is not the weight rating of the forks but the Weight of the forks. Big heavy duty forks are for big tractors and skidsteers that have a lot of lift capacity. Also I would not recommend any forks for our size tractors over 42 inch long.. That is plenty long enough. To long is just more likely to take out your garage wall. Good luck in your hunt..
James K0UA