Ive been following this as well. We are coming Colorado in July. Will be in the Grand lake area. Ive fished and hiked that area a lot and used the gazetteer maps and topos from REI. Are thos still reliable? We do have a portable GPS but not a fan of them. They are always wrong when I need them the most. I prefer to use a compass and paper maps when heading to back country. We are wanting to drive some trails while there.
I'm not aware of many of what I'd call "jeep trails" in that area since it's somewhat embedded in Rocky Mountain NP which mostly overlaps with wilderness area (no mechanical travel allowed), but it is a fairly short drive from Roosevelt and Arapaho NF and Medicine Bow/Routt NF. When I'm in NF land I use Avenza maps on my Android phone and download the USFS Motor Vehicle Use Maps for the ranger districts for the NF I'm visiting.
Outside of national forest I download the gpx files from trailsoffroad.com and import them into whatever GPS app I'm wanting to use. I usually use Backcountry Navigator with the included topo map for that. But you could import them into your GPS device as well.