Sorry for the newbie questions. I promise I have tried to research on here prior to posting (I'm surprised I couldn't find any similar discussions before).

As the title suggests there will be no wired WAN just two LTE modems setup with a load sharing algorithm (not bonding)

Would it be as simple as buying:
1 X RBM33G https://mikrotik.com/product/rbm33g
2 X Huawei ME909s-120 (Modem MiniPCI-e) http://consumer.huawei.com/solutions/m2 ... cie_en.htm
4 X pigtails
1 X Case
1 X power

If you have any suggestions or any reference to other projects I would be grateful to hear of them

looks like i will have to just take the plunge?

Why would you think that the LTE modems are different than other interfaces? I do load balancing over 2 ethernet interfaces and a 3g modem. The only difference is the weight associated to distribution of traffic. Everything else works the same.