I think the loft and ramp part is cool however, it takes away half of the floor space for your pig. Best is to add another grid in the width or think of another way to make a ramp upwards that doesn't block Brownie's running space. Usually the idea of the loft is to put all the food and other material away from the ground floor making more space to run leaving only a few toys and maybe a pigloo to play with. By centering all items your pig gets to run around it using the space to it's fullest.

Also you might want to consider adopting Brownie a friend (Not sure if he has?) as guinea pigs are herd animals and are healthier and happier with a companion.