Since Ground Tomes were added to Garlaige Citadel, the Chamber Beetles in the large lower room you drop into have been replaced by higher level beetles you should be 95+ to take on - Chamber Beetles will be harder to come by easily.
Chamber Beetles behind Banishing Gate#2 all check EP at level 99 and there is enough for this trial.
Batallia Downs (S) vs. Forester Beetle. Area in Northwest corner where Lumber Jack spawns in present time. there 17 beetles in that small area with a quick respawn timer, but you will need a sync under 65. they are only 47-50 range.
Sauromugue Champaign (S) vs Gouger Beetle. They check Tough to a level 90 character, and there are about 20 of them in the NE part of the map. As almost every zone in the past, weather can be frequent. Can get earth weather there.
Ordelle's Caves vs Targe Beetle. They check Decent Challenge to a level 90 character, lots of spawns. They spawn on Map 1 at F/G-12 and H/I-12 (in the area up the cliff that you drop through the hole to get to). Water weather is frequent but it can be wind as well (that will not count unfortunately).