https://photos.app.goo.gl/ovhiXAM4kzndNcwC9

Here's an album I created of some of the harnesses we use and like. Cora is the fawn merle and she is around 108 lbs. River is the harlequin and she is around 120 lbs, about 37" around the deepest part of her chest and 32" from base of neck to base of tail.

The basic harness that is black with a hot pink accent is a Balance Harness by Blue-9 in size large. It is very adjustable and has two points of connection, one at the rear and one at the front. You can use it with a euro leash such as this one, so there will always be equal pressure on each leash attachment.

The pink and orange harnesses are the Front-Range harness by Ruffwear and both are in size L/XL. Like the Balance harness, it also has two leash connection points. In some of the pictures of River in her Front Range harness, you'll see there's a short traffic lead attached to a head collar and clipped to the front leash attachment with a carabiner. River struggles with leash manners when we're passing other hikers/dogs, so this set up gives me control when I need it and keeps the handle in place.

The red harness is the Web master harness in size L/XL, also from Ruffwear. I'm currently using it as a mobility harness for my German Shepherd, so I didn't cinch all the straps properly on River. There is only one leash attachment in the back, no front attachment. There is a handle that is great for helping your dog over obstacles, which is why it makes a great mobility or hiking harness. The Web master is probably most similar to the feel of a backpack for your dogs, so it may be a good stepping stone if you think they'd need it. I would say it's a very good option for hiking, provided your dogs already have basic leash manners.