This topic has been covered before but I thought I would post my findings in case it helps someone...
The following companies offer "agreed value" policies which cover an agreed upon value with no depreciation but they said that JKs are not eligible because they do not qualify as classic vehicles or collector vehicles...
The following companies said that either they do not cover modifications at all or they do not cover extensive modifications but some of them consider vehicles on a case-by-case basis so this may depend on your agent...
The following companies offer "actual cash value" policies which cover book values which factor in depreciation and they said they will cover modifications but they have fairly low limits on how much they will cover...
Allstate ($1,000 Custom Parts And Equipment)
Esurance ($4,000 Custom Parts And Equipment)
The following companies offer "actual cash value" policies and they said they do cover modifications but they have a range of coverage amounts and you will pay higher premiums for additional coverage on your modifications...
Liberty Mutual ($500 To $25,000 Custom Parts And Equipment)
Progressive ($1,000 To $5,000 Custom Parts And Equipment)
The following companies offer "stated value" policies that cover up to the stated value but they said that depreciation is factored in so these policies do not guarantee the full stated amount like "agreed value" policies do...
Progressive (Use Stated Value When $5,000 Is Not Enough)
So if you have $10,000 in modifications your only options in Florida appear to be Liberty Mutual with extra custom parts and equipment coverage or Progressive with stated value coverage. I personally prefer the wording on the Liberty Mutual policy because it explicitly covers modifications. With the stated value policy from Progressive you would need to carefully read the policy to make sure there are no exclusions, you might end up jumping through more hoops at claims time, and you would want to update the stated value each year so you aren't overpaying. But Liberty Mutual can be as much as $1,000 more in premiums per year so maybe the stated value policy with Progressive is worth the inconvenience. I'm still not sure which policy I will go with so any feedback is appreciated!
Also note that there are some other things to consider. Some companies simply won't insure vehicles with certain size lifts, some companies have exclusions for specific modifications like racing changes, and most companies will not cover damage incurred due to off-roading. So make sure to do your own research and let me know if you've found anything different. Thanks!