I can't have eggs, do you think I can use an egg replacement like Bob's Red Mill egg replacer?

In years as a vegetarian, I successfully used soft tofu as an egg replacement in breads, cakes and sauces. In other words, where the tofu worked for emulsion and aeration, but flavor came from other ingredients.
So, it might work in these lemon bars but won’t give the texture and taste the eggs would have provided.

There is a plant based liquid egg substitute called Just Egg that would be ideal for this recipe. https://www.ju.st/cook

I would also recommend adding coconut to a naturally egg-free recipe like:
https://www.noracooks.com/vegan-lemon-bars/#wprm-recipe-container-5401
https://minimalistbaker.com/creamy-vegan-lemon-bars/#wprm-recipe-container-35359

As a bonus, both use coconut milk or cream, which would amp up the coconut flavor.

Eggs are such a big part of the filling that I think you might be better off using an egg-free recipe for lemon bars instead. You could still try to use an egg replacer like the one from Bob's, if you wanted. One other thing you would want to add in is some sort of color- because without the yellow yolk, your bars might well end up a rather unappetizing greyish color. I'd suggest using a recipe which calls for thickening evaporated milk with lemon juice instead, and adding in a few drops of yellow coloring or even a dash of turmeric. There's no reason why you couldn't stir the coconut into one of those sort of recipes.